Podcasts about chemie und pharmazie

Fakultät für Chemie und Pharmazie - Fakultätsbroschüre

Sat, 1 Oct 1994 12:00:00 +0100 http://epub.ub.uni-muenchen.de/8719/ http://epub.ub.uni-muenchen.de/8719/1/Mueller_Guenter_8719.pdf Müller, Günter; Wetekam, Eva-Marlen; Jung, Christian; Bandlow, Wolfhard Müller, Günter; Wetekam, Eva-Marlen; Jung, Christian und Bandlow, Wolfhard (Oktober 1994): Membrane Association of Lipoprotein Lipase and a cAMP-Binding Ectoprotein in Rat Adipocytes. In: Biochemistry, Vol. 33, Nr. 40: pp. 12149-12159.

Thu, 1 Sep 1994 12:00:00 +0100 http://epub.ub.uni-muenchen.de/8714/ http://epub.ub.uni-muenchen.de/8714/1/Mueller_Guenter_8714.pdf Müller, Günter; Dearey, Elisabeth Ann; Korndörfer, Andrea; Bandlow, Wolfhard Müller, Günter; Dearey, Elisabeth Ann; Korndörfer, Andrea und Bandlow, Wolfhard (September 1994): Stimulation of a glycosyl-phosphatidylinositol-specific phospholipase by insulin and the sulfonylurea, glimepiride, in rat adipocytes depends on increased glucose transport. In: The Journal of Cell

The long-term hypoglycemic activity of sulphonylurea drugs has been attributed, in part at least, to the stimulation of glucose utilization in extra-pancreatic tissues. The novel sulphonylurea, glimepiride, gives rise to a longer lasting reduction in the blood sugar level in dogs and rabbits compared to glibenclamide (Geisen K, Drug Res38: 1120–1130, 1988). This cannot be explained adequately by elevated plasma insulin levels. This study investigated whether this prolonged hypoglycemic phase was based on the drug's abilities to stimulate glucose utilization and affect the underlying regulatory mechanisms in insulin-sensitive cells in vitro. It was found that in the absence of added insulin, glimepiride and glibenclamide (1–50 μM) stimulated lipogenesis (3T3 adipocytes) and glycogenesis (isolated rat diaphragm) not, vert, similar4.5- and 2.5-fold, respectively, and reduced the isoproterenol-stimulated lipolysis (rat adipocytes) up to 40–60%. The increased glucose utilization was correlated with a 3–4-fold higher 2-deoxyglucose transport rate and amount of GLUT4 at the plasma membrane, as well as with increased activities of key metabolic enzymes (glycerol-3-phosphate acyltransferase, glycogen synthase) within the same concentration range. Furthermore, the low Km cAMP-specific phosphodiesterase was activated 1.8-fold, whereas the cytosolic cAMP level and protein kinase A activity ratios were significantly lowered after incubation of isoproterenol-stimulated rat adipocytes with the sulphonylureas. In many of the aspects studied the novel sulphonylurea, glimepiride, exhibited slightly lower ed50-values than glibenclamide. This study demonstrates correlations existing between drug-induced stimulation of glucose transport/metabolism and cAMP degradation/protein kinase A inhibition as well as between the relative efficiencies of glimepiride and glibenclamide in inducing thse extra-pancreatic processes. Therefore, it is suggested that the stimulation of glucose utilization by sulphonylureas is mediated by a decrease of cAMP-dependent phosphorylation of GLUT4 and glucose metabolizing enzymes. The therapeutic relevance of extra-pancreatic effects of sulphonylureas, in general, and of the differences between glimepiride and glibenclamide as observed in vitro in this work, in particular, remain to be elucidated.

Glimepiride is a novel sulfonylurea for the treatment of type II-diabetic patients exhibiting different receptor binding kinetics to β-cell membranes with 8–9-fold higher koff rate and 2.5–3-fold higher kon rate compared to glibenclamide (see accompanying paper (Müller, G. et al. (1994) Biochim. Biophys. Acta 1191, 267–277)). To elucidate the molecular basis for this differential behaviour of glimepiride and glibenclamide, direct photoaffinity labeling studies using β-cell tumor membranes were performed. [3H]Glimepiride was specifically incorporated into a membrane polypeptide of Mr = 65000 under conditions, which led to predominant labeling of a 140 kDa protein by [3H]glibenclamide (Kramer, W. et al. (1988) FEBS Lett. 229, 355–359). Labeling of the 140 kDa protein by [3H]glibenclamide was inhibited by unlabeled glimepiride and, vice versa, glibenclamide inhibited labeling of the 65 kDa protein by [3H]glimepiride. The 65 kDa protein was also specifically photolabeled by the sulfonylurea [125I]35623, whereas an 4-azidobenzoyl derivative of glibenclamide, N3-[3H]33055, exclusively labeled a 33 kDa protein. Competitive Scatchard analysis of [3H]glimepiride-binding and [3H]glibenclamide-binding to RINm5F cell membranes using glibenclamide and glimepiride, respectively, as heterologous displacing compounds yielded non-linear plots. These findings may be explained by cooperative interactions between the 140 and 65 kDa sulfonylurea-binding proteins. The possibility that sulfonylureas of different structure have different access to the 140 and 65 kDa receptor proteins due to the β-cell membrane barrier was investigated by photoaffinity labeling of solubilized β-cell membrane proteins. Interestingly, solubilization of β-cell tumor membranes led to a shift of specific [3H]glibenclamide binding from the 140 kDa to the 65 kDa binding protein, exclusively, and to an increased labeling of the 65 kDa protein by [3H]glimepiride. The labeling of a unique protein is in agreement with similar Kd values measured for both sulfonylurcas upon solubilization of β-cell tumor and RINm5F cell membranes (see accompanying paper). Furthermore, competitive Scatchard plots of [3H]glimepiride binding to solubilized RINm5F cell membrane proteins in the presence of glibenclamide and vice versa approximate linearity suggesting loss of cooperativity between the 140 kDa glibenclamide-binding and 65 kDa glimepiride-binding proteins upon solubilization. The physiological significance of the differential interaction of glimepiride and glibenclamide with different binding proteins was also substantiated by photoaffinity labeling of RINm5F cells leading to labeling of a 140 kDa protein by [3H]glibenclamide and of a 65 kDa protein by [3H]glimepiride. In conclusion, this report presents the first evidence that different sulfonylurea drugs bind to different components of the sulfonylurea receptor complex which are characterized by different accessibility for the drugs.

Glycosyl-phosphatidylinositol-anchored membrane proteins (GPI-proteins) are normally identified either by cleavage of the lipid anchor using (glycosyl)phosphatidylinositol-specific phospholipases C or D (GPI-PLs) or by metabolic labeling of the lipid moiety with specific building blocks. Therefore, methods for discrimination between transmembrane proteins and GPI-proteins on the basis of their physicochemical properties are desirable. Here we are presenting a selective extraction method for typical well-characterized mammalian GPI-proteins, e.g., acetylcholine esterase, alkaline phosphatase, 5′-nucleotidase, and lipoprotein lipase, using a derivative of taurocholate. The results were compared to those obtained with well-characterized transmembrane proteins, e.g., insulin receptor and hydroxymethyl glutaryl coenzyme A-reductase, glucose transporters, or aminopeptidase M and several commercially available detergents. With regard to total membrane proteins, it was possible to selectively enrich GPI-proteins up to 8- to 14-fold by using concentrations between 0.1 and 0.3% of 4′-NH2-amino-7β-benzamido-taurocholic acid (BATC). In addition, the cleavage specificity and efficiency of (G)PI-PLs were increased in the presence of identical concentrations of BATC compared to commonly used detergents, e.g., Nonidet P-40. Therefore, the present study shows that the use of BATC facilitates the identification of glycosyl-phosphatidylinositol-anchored membrane proteins.

(1,2,3,4,5)Pentachlorferrocen reagiert mit Butyllithium und anschließend mit MeSSMe zu [C5Cl4(SMe)]FeCP (Cp = η5-C5H5) (1). Durch Wiederholung dieser Prozedur lassen sich [C5Cl3(SMe)2]FeCp (2) und [C5Cl2(SMe)3]FeCp (3) erhalten. Eine Kristallstrukturanalyse von 2 zeigt eine 1,3-Anordnung der beiden SMe-Gruppen. Eine Anzahl unsymmetrischer Cymantrenbis- und tristhioether (4–6) wurde auf ähnliche Weise aus [C5Cl4(SR)]Mn(CO)3 bzw. [C5Cl3(SR)2]Mn(CO)3 (R = Me, Ph) dargestellt. Auch Cymantrenyl-Selenoether [C5Cl5−n(SeR)n]Mn(CO)3 (7–10) (R = Me, n = 1, 2, 3; R = Ph, n = 2) konnten erhalten werden.

The encapsulation of graphite-type carbon wires in the regular, 3-nanometer-wide hexagonal channels of the mesoporous host MCM-41 is reported. Acrylonitrile monomers are introduced through vapor or solution transfer and polymerized in the channels with external radical initiators. Pyrolysis of the intrachannel polyacrylonitrile results in filaments whose microwave conductivity is about 10 times that of bulk carbonized polyacrylonitrile. The MCM host plays a key role in ordering the carbon structure, most likely through the parallel alignment of the precursor polymer chains in the channels. The fabrication of stable carbon filaments in ordered, nanometer-sized channels represents an important step toward the development of nanometer electronics.

Sat, 1 Jan 1994 12:00:00 +0100 http://epub.ub.uni-muenchen.de/4221/ http://epub.ub.uni-muenchen.de/4221/1/080.pdf Feng, Sue; Bein, Thomas Feng, Sue und Bein, Thomas (1994): Vertical Aluminophosphate Molecular Sieve Crystals Grown at Inorganic-Organic Interfaces. In: Science, Vol. 265: pp. 1839-1841. Che

Sat, 1 Jan 1994 12:00:00 +0100 http://epub.ub.uni-muenchen.de/4222/ http://epub.ub.uni-muenchen.de/4222/1/084.pdf Wu, Chun-Guey; Bein, Thomas Wu, Chun-Guey und Bein, Thomas (1994): Conducting Polyaniline Filaments in a Mesoporous Channel Host. In: Science, Vol. 264: pp. 1757-1759. Chemie und Pharmazie

Sat, 1 Jan 1994 12:00:00 +0100 http://epub.ub.uni-muenchen.de/4224/ http://epub.ub.uni-muenchen.de/4224/1/081.pdf Kurth, Dirk G.; Broeker, Gregory K.; Kubiak, Clifford P.; Bein, Thomas Kurth, Dirk G.; Broeker, Gregory K.; Kubiak, Clifford P. und Bein, Thomas (1994): Surface Attachment and Stability of Cross-Linked Poly(ethylenimine)-Epoxy Networks on Gold. In: Chemistry of Materials, Vol. 6, Nr. 11: pp. 2143-2150. C

Sat, 1 Jan 1994 12:00:00 +0100 http://epub.ub.uni-muenchen.de/4225/ http://epub.ub.uni-muenchen.de/4225/1/083.pdf Wu, Chun-Guey; Bein, Thomas Wu, Chun-Guey und Bein, Thomas (1994): Polyaniline Wires in Oxidant-Containing Mesoporous Channel Hosts. In: Chemistry of Materials, Vol. 8, Nr. 6: pp. 1109-1112. Chemie und Pharmazie

Sat, 1 Jan 1994 12:00:00 +0100 http://epub.ub.uni-muenchen.de/4227/ http://epub.ub.uni-muenchen.de/4227/1/085.pdf Feng, Sue; Bein, Thomas Feng, Sue und Bein, Thomas (1994): Growth of oriented molecular sieve crystals on organophosphonate films. In: Nature, Vol. 368: pp. 834-836. Chemie und Pharmazie

[C5Br5]Mn(CO)3 reacts with butyl lithium and one equivalent of SiMe2Cl2 to yield [C5Br4SiMe2Cl]Mn(CO)3 (1). The reaction of 1 with [C5X4Li]Mn(CO)3 (X=Br, Cl) gives the bimetallic compounds (OC)3Mn(C5Br4--- SiMe2---C5X4)Mn(CO)3 (X=Br (2), Cl (3))·2 can also be obtained by reaction of two equivalents of [C5Br4Li]- Mn(CO)3 with one equivalent of SiMe2Cl2· [C5Cl4Li]Mn(CO)3 reacts with Cp2TiCl2, depending on the reaction conditions, to yield the bi- and trimetallic compounds [C5Cl4TiCp2Cl]Mn(CO)3 (4) and (OC)3Mn(C5Cl4--- TiCp2---C5Cl4)Mn(CO)3 (5). The molecular structures of 2 and 5 have been determined by X-ray crystallography.

When [C5Br5]Mn(CO)3 (1) is treated with butyllithium and hydrolysed after some time, one can always obtain more than one product, independent of stoichiometry, solvent, temperature and lithiation time. However, the distribution of products strongly depends on the reaction conditions. For example, in THF, with a tenfold excess of butyllithium at −78°C, a conversion of more than 80% into [C5H5]Mn(CO)3 can be achieved. In IC5 Cl4Br]Mn(CO)3 (2) only a maximum of two halogens can be substituted by hydrogen. These results can be explained in terms of the competition between butyl lithium and the lithiated species [C5X4Li]Mn(CO)3 in the halogen-metal exchange reaction.

Dichloroethyne ClCECCl reacts with Pt(PPh3)2(C2H4) or Pt(PPh& to give the a-complex Pt(PPh3)2(+21C=CC1) (l),w hich can be isomerized by prolonged refluxing in toluene to trans- (Ph3P)zC1Pt-C==CC1 (2). 2 easily undergoes exchange reactions with alkylphosphines and with halide anions to yield trans-(R3P)2ClPt-C=CCl (R = Et (3)) Bu (4)) and trans-(Ph3P)z- (X)Pt-C=CCl (X = F (5a), Br (5b), I (5c)), respectively. The alkylphosphine complexes 3 and 4 can also be obtained by reaction of Pt(PR3)4 (R = Et, “Bu) with ClCECCl or from 1 and the corresponding phosphine. When Pt(PPh&(CzH4) is added to a solution of 3, a dinuclear complex 6 is formed, in which the C=C-Cl group acts as a a,a-bridging ligand. Upon standing, oxidative addition of the remaining C-C1 bond occurs and the p-ethynediyl complex trans- C1(R3P)2Pt-C=C-Pt(PPh3)2C1-Cis (R = Et (7a)) can be obtained. The corresponding p-ethynediyl complex 7b (R = Ph) is formed directly from 2 and Pt(PPh&(CzH4). 7b isomerizes upon heating in toluene to the symmetrical all-trans isomer 8. The molecular structures of 1 and 8 were determined by X-ray diffraction (1: C ~ ~ H ~ ~ C ~ Z P ~ Pa ~=C 10H.3Z11C(3~) AZ,, b = 10.392(4) A, c = 33.675(16) A, P = 90.17(3)’, monoclinic, P21/n, 2 = 4. 8: C74H&1zP4Ptz9 a = 12.938(2) A, b = 19.964(3) A, c = 24.844(3) A, P = 96.14(1)’, monoclinic, C2/c, 2 = 4).

Metal Complexes of Biologically Important Ligands, LXX[1].- Synthesis, Stereochemistry and Reactions of Ruthenium(II) and Osmium(II) Complexes with -Amino Carboxylates[Note ][Herrn Professor Helmut Werner zum 60. Geburtstag gewidmet.] The reactions of MHCl(CO)(PPh3)3 with salts of -amino acids give the hydrido-N,O-chelate complexes MH(CO)(NH2CHR-COO)(PPh3)2 (1a-g;) M = Ru, Os). Complexes 1a-c can alternatively be prepared by oxidative addition of the appropriate -amino acid to Ru(CO)3(PPh3)2. The crystal structure of 1b has been determined by an X-ray structural analysis. The leucinato compound 1c is an effective catalyst for the decomposition of formic acid. In contrast, reactions of RuHCl-(CO)(PPh3)3 with -amino acids afford the chloro-N,O-che-late complexes RuCl(CO)(NH2CHRCOO)(PPh3)2 2a-h. The decomposition reactions of 2c, 2g and2h have been investigated.

Sat, 1 Jan 1994 12:00:00 +0100 http://epub.ub.uni-muenchen.de/4169/ http://epub.ub.uni-muenchen.de/4169/1/077.pdf Huber, Christian; Moller, Karin; Bein, Thomas Huber, Christian; Moller, Karin und Bein, Thomas (1994): Encapsulation of Tetracarbonyl(trimethylstannyl)cobalt in NaY Zeolite. Reactivity and Alloy Cluster Formation. In: Journal of Physical Chemistry, Vol. 98, Nr. 46: pp. 12067-12074.

Hydrocarbon-Bridged Complexes, XXX. - Nucleophilic Addition of Carbonylmetallates to Cationic Vinyl, Diene, Dienyl and Triene Complexes of Iron, Ruthenium and Cobalt: Di-, Tri-, Tetra- and Pentametallic Complexes with ,- and ,-Hydrocarbon Bridges[Note ][Herrn Professor Ekkehard Lindner zum 60. Geburtstag gewidmet.] The reactions of [Re(CO)5]-, [Ru(CO)2Cp]-, and [Os(CO)4]2- with [Cp2(OC)2Fe2(-CO)(-1:2-CH=CH2)]+, [Cp*Ru(2:4-1,3,7-octatriene)]+, [(OC)Fe(4-diene)(5-cycloheptadienyl)]+, and [CpCo(5-cyclodienyl)]+ give the nucleophilic adducts whereas with [Mn(CO)5]-, [W(CO)3Cp]-, and [Fe(CO)2Cp]- formation of the corresponding C-C coupling products and of the metal-metal-bonded dimers is observed. The structures of Cp*Ru(-1:2:3-1,5-octadienyl)Re(CO)5 (4), [Cp* Ru(-1:2:3-1,5-octadienyl)]2Os(CO)4 (6), and of (OC)-Fe(4-1,3-cyclohexadiene) (-1:4-1,3-cycloheptadiene)Re(CO)5 (9) have been determined by X-ray diffraction.

Eliminierung von HCl aus dem sechsfach koordinierten Komplex Cl2(Ph3P)2 liefert den α-Acylesterenolat-Komplex (Cl)Ph3P)2 (1) mit der Koordinationszahl 5. Die Röntgenstrukturanalyse zeigt für 1 eine verzerrte tetragonal pyramidale Struktur mit der Acylgruppe an der Spitze. An den 16-Elektronen-Komplex 1 lassen sich (reversibel) CO und CH3CN addieren.

The binding of hexo-/glucokinase and glycerol kinase to mitochondria via the channel forming protein, porin, in pancreatic islet β-cells and adipocytes, was recently proposed to participate in nutritional signaling, glucose sensing, and the control of high-energy phosphate distribution and oxidative phosphorylation. In this study we demonstrate that polyclonal antisera against purified rat liver porin recognize unique proteins in rat pancreatic islets, adipocytes, and RINm5F cells, each with an apparent Mr about 2000 smaller than that of liver porin. Immunoblotting of subcellular fractions, the purity of which has been controlled by the distribution of marker proteins, revealed the mitochondrial localization of the cross-reacting proteins. Their enrichment with a method used for the purification of porin proteins, the characteristic behavior during isoelectric focusing, and the specific binding of rat liver hexokinase and glycerol kinase to phospholipid vesicles containing the purified cross-reacting β-cell or adipocyte proteins strongly suggest their identity with mitochondrial porin. The subtle differences in the apparent Mr and charge heterogeneity raise the possibility of the existence of porin isoforms expressed in a tissue-specific manner. Anti-porin antisera coimmunoprecipitated hexo-/glucokinase from rat insulinoma cell (RINm5F) and adipocyte mitochondria as determined by subsequent immunoblotting of the immunoprecipitates with polyclonal antisera against yeast hexokinase and rat liver glucokinase, respectively. This indicates that some rat pancreatic glucokinase (54 kDa) and liver hexokinase (102 kDa), respectively, is bound to mitochondrial porin. The major portion of the bound fraction is released from mitochondria after treatment with glucose 6-phosphate. Incubation of RINm5F and fat cells with the insulin releasing sulfonylurea drug, glimepiride (20 nM and 5 μM, respectively) for 30 min reduces the amount of hexo-/glucokinase associated with mitochondria and porin to about 50-30%. The reduced kinase binding activity of porin is preserved after isolation of porin from glimepiride-treated cells, reconstitution into phospholipid vesicles and assaying for glucose 6-phosphate inhibitable binding of rat liver hexokinase. The sulfonylurea tolbutamide (20 μM and 5 mM) is significantly less effective. The sulfonylurea-induced inhibition of hexo-/glucokinase binding to mitochondrial porin does not require glucose metabolism or Ca2+ influx into the cells. These data suggest that the sulfonylurea glimepiride, which is thought to inhibit the ATP-regulated K+-channel in β-cells, may have, in addition, an intracellular site of action in pancreatic islet and adipocyte cells at the level of regulation of gluco-/hexokinase binding to mitochondrial porin.

Two new cAMP-binding proteins have been discovered recently in Saccharomyces cerevisiae. They are genetically distinct from the regulatory subunit of cytoplasmic cAMP-dependent protein kinase A and are distinguished from the latter, in addition, by their anchorage through phosphatidylinositol-containing lipid and glycolipid structures to mitochondrial and plasma membranes, respectively (Müller and Bandlow, 1989 Biochemistry 28, 9957-9967, 1991, Biochemistry 30, 10181-10190). A nutritional upshift induces the cleavage of the anchor by a phospholipase C (Müller and Bandlow, 1993, J. Cell Biol. 122, 225-236). To test the idea that anchorage by (glycosyl)phosphatidyl-inositol influences cAMP-binding and has a regulatory function, we analyzed ligand binding to the two purified cAMP receptors (46,000 and 54,000 Da) in comparison to the regulatory subunit of the cytoplasmic protein kinase A (52,000 Da). We find that lipolytic cleavage of the two membrane anchors by phosphatidylinositol-specific phospholipases C and D results in significantly higher association and lower dissociation rates of cAMP, thus leading to a dramatic increase in ligand affinity of the two cAMP receptors. Use of cAMP analogues identifies two different cAMP-binding centers in each membrane-embedded protein, one of which is noticeably affected by the cleavage of the anchor. In both phosphatidylinositol-anchored cAMP receptor proteins a single Trp residue in one of the binding centers is photoaffinity-labeled by 8-N3-cAMP, whereas two amino acids, Trp and Tyr, are modified after lipolytic removal of the anchor. The differences in the labeling patterns are interpreted as to result from a conformational rearrangement induced by the cleavage of the anchor. Together with the increased affinity to the ligand these changes document alterations of the properties and folding structure of lipid-anchored proteins following cleavage of the PI-containing anchor by specific phospholipases and provide the first molecular evidence for a regulatory role of the anchorage by a lipid structure. The cytoplasmic regulatory subunit of yeast protein kinase A is not photolabeled to a significant extent under any condition.

Glimepiride is a novel sulfonylurea drug for treatment of non-insulin-dependent diabetes mellitus with higher blood sugar lowering efficacy in diabetic patients than glibenclamide raising the question whether this characteristics is in line with different binding of glimepiride and glibenclamide to the β-cell sulfonylurea receptor. Scatchard plot analysis of [3H]sulfonylurea binding to membranes isolated from rat β-cell tumors and (RINm5F) insulinoma cells and to RINm5F cells demonstrated that glimepiride has a 2.5–3-fold lower affinity than glibenclamide. This corresponded well to the 8–9-fold higher koff and 2.5–3-fold higher kon rates of glimepiride compared to glibenclamide as revealed by the dissociation and association kinetics of [3H]sulfonylurea binding and the Kd values calculated thereof. In agreement, the concentrations required for half-maximal displacement of [3H]sulfonylurea bound to β-cell membranes were significantly higher for glimepiride compared to glibenclamide. However, the binding affinity of glimepiride measured by both equilibrium binding and kinetic binding studies upon solubilization of β-cell tumor membranes and RINm5F cell membranes increased up to the value for glibenclamide. This was primarily based on a drastic decrease of the dissociation rate constant of glimepiride whereas the kinetics of glibenclamide binding remained largely unaffected upon solubilization. These data suggest that the Kd value alone is not sufficient for characterization of a sulfonylurea drug, since the kinetic binding parameters may also determine its acute blood sugar lowering efficacy.

Sat, 1 Jan 1994 12:00:00 +0100 http://epub.ub.uni-muenchen.de/4170/ http://epub.ub.uni-muenchen.de/4170/1/079.pdf Huber, Christian; Moller, Karin; Ogunwumi, Steven B.; Bein, Thomas Huber, Christian; Moller, Karin; Ogunwumi, Steven B. und Bein, Thomas (1994): Bimetallic Complexes in Zeolites. Reactivity of Tetracarbonyl(trimethylstannyl)cobalt in Acidic Zeolite Y. In: Journal of Physical Chemistry, Vol. 98, Nr. 51: pp. 13651-13657.

An enzyme system catalysing the formation of the methylenedioxy bridge at ring A of (S)-canadine [ = (S)-tetrahydroberberine] from (S)-tetrahydrocolumbamine has been detected in microsomal preparations from different Ranunculaceae and Berberidaceae cell cultures. The cytochrome P-450 enzyme complex has been partly characterized from a protoberberine alkaloid producing Thalictrum tuberosum L. cell line. The enzyme complex consisting of a microsomal associated oxidase with a cytochrome P-450 reductase has a pH optimum at pH 8.5 and a temperature optimum of 40°. The apparent Km values are 33 μM for NADPH and 11.5 μM for tetrahydrocolumbamine.

Sat, 1 Jan 1994 12:00:00 +0100 http://epub.ub.uni-muenchen.de/3652/ http://epub.ub.uni-muenchen.de/3652/1/3652.pdf Singer-Lahat, Dafna; Lotan, Ilana; Biel, Martin; Flockerzi, Veit; Hofmann, Franz; Dascal, Nathan Singer-Lahat, Dafna; Lotan, Ilana; Biel, Martin; Flockerzi, Veit; Hofmann, Franz und Dascal, Nathan (1994): Cardiac calcium channels expressed in Xenopus oocytes are modulated by dephosphorylation but not by cAMP-dependent phosphorylation. In: Receptors and Channels, Vol. 2: pp. 215-226.

Sat, 1 Jan 1994 12:00:00 +0100 http://epub.ub.uni-muenchen.de/4054/ http://epub.ub.uni-muenchen.de/4054/1/035.pdf Plank, Christian; Oberhauser, Berndt; Mechtler, Karl; Koch, Christian; Wagner, Ernst Plank, Christian; Oberhauser, Berndt; Mechtler, Karl; Koch, Christian und Wagner, Ernst (1994): The influence of endosome-disruptive peptides on gene transfer using synthetic virus-like gene transfer systems. In: Journal of Biological Chemistry, Vol. 269: pp. 12918-12924.

Sat, 1 Jan 1994 12:00:00 +0100 http://epub.ub.uni-muenchen.de/3654/ http://epub.ub.uni-muenchen.de/3654/1/3654.pdf Distler, Madeleine; Biel, Martin; Flockerzi, Veit; Hofmann, Franz Distler, Madeleine; Biel, Martin; Flockerzi, Veit und Hofmann, Franz (1994): Expression of cyclic nucleotide-gated cation channels in non-sensory tissues and cells. In: Neuropharmacology, Vol. 33: pp. 1275-1282. Chemi

Competition experiments have been performed to determine the relative reactivities of 23 alkyl chlorides toward allyltrimethylsilane in the presence of catalytic amounts of ZnCl2.The krel scale spans over 11 orders of magnitude from 1-adamantyl chloride (least reactive) to bis(p-methoxyphenyl)methyl chloride (most reactive compound). A fair correlation between the alkylating ability and the SN1 reactivity in solvolysis reactions is found, thus providing a quantitative basis for our long-standing working hypothesis that Lewis acid-catalyzed additions of alkyl halides to CC multiple bonds only yield 1:1 products if the reactants ionize faster than the products. Trityl chlorides do not follow this correlation and are 105 times less reactive than predicted from their SN1 reactivities.

Competition experiments have been performed to determine the relative reactivities of acetals and ethers toward allyltrimethylsilane in the presence of catalytic amounts of BF3 OEt2. It is found that acetals R-CH(OMe)2 and their phenylogous p-anisyl ethers R-CH(p-MeOC6H4)(OMe) show very little differences in reactivity. The reactivity scales are employed to rationalize the results of Lewis acid-catalyzed additions of acetals and ethers to CC double bonds.

Relative reactivities of alkenes and alkynes toward diarylmethyl cations have been determined by direct rate measurements and by competition experiments in dichloromethane. At -70°C alkynes are found to be one to two orders of magnitude less reactive than analogously substituted alkenes (e.g. phenylacetylene/styrene), but the reactivity difference reduces strongly as the temperature is raised. The stereochemistry of the vinyl chlorides produced by addition of benzhydryl chlorides to alkynes is characterized.

Second-order rate constants for the reactions of the ferrocenylmethylium ions 2a - e with silyl enol ethers, allylsilanes, allylstannanes, and hydride donors have been determined photometrically and conductometrically in dichloromethane. The ferrocenylmethylium ions 2a - d (fc-CHR+, R = H, Me, Ph, An) are slightly stronger electrophiles than the tropylium ion, and their electrophilic reactivities depend only slightly on the nature of R. The bis(ferrocenyl)methylium ion 2e is a considerably weaker electrophile, comparable to the tricarbonyl(cyclohexadienyl)iron cation.

Sat, 1 Jan 1994 12:00:00 +0100 http://epub.ub.uni-muenchen.de/3940/ http://epub.ub.uni-muenchen.de/3940/1/122.pdf Roth, Michael; Schade, Christian; Mayr, Herbert Roth, Michael; Schade, Christian und Mayr, Herbert (1994): Kinetics of carbenium ion additions to methylenecycloalkanes. Cycloalkyl cation stabilities are not predominantly controlled by strain. In: Journal of Organic Chemistry, Vol. 59, Nr. 1: pp. 169-17

Sat, 1 Jan 1994 12:00:00 +0100 http://epub.ub.uni-muenchen.de/3941/ http://epub.ub.uni-muenchen.de/3941/1/125.pdf Mayr, Herbert; Baran, Janusz; Will, Elfriede; Yamakoshi, Hideyuki; Teshima, Koichi; Nojima, Masatomo Mayr, Herbert; Baran, Janusz; Will, Elfriede; Yamakoshi, Hideyuki; Teshima, Koichi und Nojima, Masatomo (1994): Exceptionally Stable Ozonides. Influence of Methyl Substituents on the Course of Cyclopentene Ozonolyses and on the Reactivities of Ozonides. In: Journal of Organic Chemistry, Vol. 59, Nr. 17: pp. 50

Epstein-Barr virus (EBV) is a herpesvirus that transforms B-cells (B-LCL) and has undergone intense scrutiny owing to its association with Burkitt's lymphoma, nasopharyngeal carcinoma, and immunoblastic lymphomas. B-LCL have also proven useful in the study of human immunology. We describe a novel system for inducing efficient foreign gene expression in B-LCL using biotinylated adenovirus as an endosome-disrupting agent. Plasmid DNA is coupled to the exterior of viral particles by streptavidin-polylysine chimeric proteins. Up to 67% of B-LCL may be induced to express foreign genes in vitro in transient expression systems, and gene expression lasts for at least 17 days. We have expressed firefly luciferase, β-galactosidase (β-gal), chloramphenicol acetyltransferase, HIV gag, and env genes, as well as infectious HIV, and the EBV-specific BZLF gene in B-LCL with this system. In vivo delivery of a β-gal reporter gene to B-LCL was documented in a SCID mouse model. Potential applications include study of genetic regulation of EBV infection and transformation events, study of potential gene therapies for EBV-related B-cell tumors, and production of antigen-presenting cells for use in immunologic assays. Because of the high percentage of cells transformed and the length of foreign gene expression, the possibility of examining foreign gene expression in transient assays, without selection for clonal populations, exists.

Sat, 1 Jan 1994 12:00:00 +0100 http://epub.ub.uni-muenchen.de/4024/ http://epub.ub.uni-muenchen.de/4024/1/4024.pdf Noe, Christian R.; Knollmüller, Max; Miculka, Christian; Dungler, Karin; Wagner, Ernst; Ettmayer, Peter Noe, Christian R.; Knollmüller, Max; Miculka, Christian; Dungler, Karin; Wagner, Ernst und Ettmayer, Peter (1994): Chirale Lactole, XI. Eine Methode zur Bestimmung der Absolutkonfiguration chiraler Alkanole. In: Chemische Berichte, Vol. 127, Nr. 5: pp. 887-892.

Sat, 1 Jan 1994 12:00:00 +0100 http://epub.ub.uni-muenchen.de/4044/ http://epub.ub.uni-muenchen.de/4044/1/039.pdf Zatloukal, Kurt; Cotten, Matt; Berger, Manfred; Schmidt, Walter; Wagner, Ernst; Birnstiel, Max L. Zatloukal, Kurt; Cotten, Matt; Berger, Manfred; Schmidt, Walter; Wagner, Ernst und Birnstiel, Max L. (1994): In vivo production of human factor VII in mice after intrasplenic implantation of primary fibroblasts transfected by receptor-mediated, adenovirus-augmented gene delivery. In: Proceedings of the National Academy of Science of the

Sat, 1 Jan 1994 12:00:00 +0100 http://epub.ub.uni-muenchen.de/4055/ http://epub.ub.uni-muenchen.de/4055/1/038.pdf Cheng, Qi; Cant, Charles; Moll, Thomas; Hofer-Warbinek, Renate; Wagner, Ernst; Birnstiel, Max L.; Bach, Fritz H.; Martin, Rainer de Cheng, Qi; Cant, Charles; Moll, Thomas; Hofer-Warbinek, Renate; Wagner, Ernst; Birnstiel, Max L.; Bach, Fritz H. und Martin, Rainer de (1994): NK-kappa B subunit-specific regulation of the I kappa B alpha promoter. In: Journal of Biological Chemistry, Vol. 269: pp. 13551-13557. Chemie und Pharmazie

Sat, 1 Jan 1994 12:00:00 +0100 http://epub.ub.uni-muenchen.de/4136/ http://epub.ub.uni-muenchen.de/4136/1/033.pdf Wanner, Klaus Th.; Paintner, Franz F. Wanner, Klaus Th. und Paintner, Franz F. (1994): Asymmetric electrophilic α-amidoalkylation - 10. A new camphorimide derived chiral auxiliary for the Asymmetric Synthesis with N-acyliminium ions - preparation of aracemic 2-Substi

Transferrin, an iron-transporting serum glycoprotein, is efficiently taken up into cells by the process of receptor-mediated endocytosis. Transferrin receptors are found on the surface of most proliferating cells, in elevated numbers on erythroblasts and on many kinds of tumors. The efficient cellular mechanism for uptake of transferrin has been subverted for the delivery of low-molecular-weight drugs, protein toxins, and liposomes by linkage of these agents to transferrin or to anti-transferrin receptor antibodies. Linkage may be via chemical conjugation procedures or by the generation of chimeric fusion proteins. Transferrin conjugated to DNA-binding compounds (e.g. polycations or intercalating agents) has been successfully used for the import of DNA molecules into cells. High-level gene expression is obtained only if endosome-disruptive agents such as influenza hemagglutinin peptides or adenovirus particles are included which release the DNA complex from intracellular vesicles into the cytoplasm.

Sat, 1 Jan 1994 12:00:00 +0100 http://epub.ub.uni-muenchen.de/4059/ http://epub.ub.uni-muenchen.de/4059/1/041.pdf Thurnher, Martin; Wagner, Ernst; Clausen, Henrik; Mechtler, Karl; Rusconi, Sandro; Dinter, André; Birnstiel, Max L.; Berger, Eric G.; Cotten, Matt Thurnher, Martin; Wagner, Ernst; Clausen, Henrik; Mechtler, Karl; Rusconi, Sandro; Dinter, André; Birnstiel, Max L.; Berger, Eric G. und Cotten, Matt (1994): Carbohydrate receptor-mediated gene transfer to human T leukaemic cells. In: Glycobiology, Vol. 4: pp. 429-435. Chemie und Pharmazie

Sat, 1 Jan 1994 12:00:00 +0100 http://epub.ub.uni-muenchen.de/4060/ http://epub.ub.uni-muenchen.de/4060/1/4060.pdf Cotten, Matt; Baker, A.; Saltik, Mediyha; Wagner, Ernst; Buschle, M. Cotten, Matt; Baker, A.; Saltik, Mediyha; Wagner, Ernst und Buschle, M. (1994): Lipopolysaccharide is a frequent contaminant of plasmid DNA preparations and can be toxic to primary cells in the presence of adenovirus. In: Gene Therapy, Vol. 1: pp. 239-

Encapsulation of oligonucleotides in antibody-targeted liposomes (immunoliposomes) which bind to target cells permits intracellular delivery of the oligonucleotides. This approach circumvents problems of extracellular degradation by nucleases and poor membrane permeability which free phosphodiester oligonucleotides are subject to, but leaves unresolved the inefficiency of encapsulation of oligonucleotides in liposomes. We have coupled oligonucleotides to cholesterol via a reversible disulfide bond. This modification of oligonucleotides improved their association with immunoliposomes by a factor of about 10 in comparison to unmodified oligonucleotides. The presence of cholesteryl-modified oligonucleotides incorporated in the bilayer of liposomes did not interfere with the coupling of the targeting protein to the liposome surface. Free or cholesterol coupled oligonucleotides associated with liposomes and directed against the tat gene of HIV-1 were tested for inhibition of HIV-1 proliferation in acutely infected cells. We demonstrate that the cholesteryl-modified as well as unmodified oligonucleotides acquire the target specificity of the antibody on the liposome. Their antiviral activity when delivered into cells is sequence-specific. The activity of these modified or unmodified oligonucleotides to inhibit the replication of HIV was the same on an equimolar basis (EC50 around 0.1 μM). Cholesterol coupled oligonucleotides thus offer increased liposome association without loss of antiviral activity.

Sat, 1 Jan 1994 12:00:00 +0100 http://epub.ub.uni-muenchen.de/4063/ http://epub.ub.uni-muenchen.de/4063/1/4063.pdf Batra, R. K.; Wang-Johanning, F.; Wagner, Ernst; Garver, R. I.; Curiel, David T. Batra, R. K.; Wang-Johanning, F.; Wagner, Ernst; Garver, R. I. und Curiel, David T. (1994): Receptor-mediated gene delivery employing lectin-binding specificity. In: Gene Therapy, Vol. 1: pp. 255-260. Chemie und Pharmazie

Adenovirus entry into its host cell transiently permeabilizes the cell allowing the coentry of reagents such as DNA. We compare here adenovirus inactivation with β-propiolactone and several psoralen derivatives, seeking reagents that disrupt the viral genome without impairing the viral entry functions. No virus replication can be detected after 8-methoxypsoralen (8-MOP) modification. Viral transcription is not detectable by Northern analysis, and reverse transcriptase/PCR analysis demonstrates at least a 1000-fold decrease in viral transcription after 8-MOP treatment. Using [3H]8-MOP, the psoralen is found to enter the virus capsid and react throughout the viral genome, with approximately one psoralen modification per 100 bp of viral DNA. This inactivated adenovirus allows us to deliver DNA to target cells without interference from adenovirus gene expression or replication. Furthermore, we can now study the host cell response to adenovirus entry without the complications of adenovirus gene expression.

Sat, 1 Jan 1994 12:00:00 +0100 http://epub.ub.uni-muenchen.de/4065/ http://epub.ub.uni-muenchen.de/4065/1/047.pdf Frank, Sasa; Krasznai, Krisztina; Durovic, Srdan; Lobentanz, Eva-Maria; Dieplinger, Hans; Wagner, Ernst; Zatloukal, Kurt; Cotten, Matt; Utermann, Gerd; Kostner, Gerd M.; Zechner, Rudolf Frank, Sasa; Krasznai, Krisztina; Durovic, Srdan; Lobentanz, Eva-Maria; Dieplinger, Hans; Wagner, Ernst; Zatloukal, Kurt; Cotten, Matt; Utermann, Gerd; Kostner, Gerd M. und Zechner, Rudolf (1994): High-Level Expression of Various Apolipoprotein (a) Isoforms by "Transferrinfection". The Role of Kringle IV Sequences in the Extracellular Association with Low-Density Lipoprotein. In:

Sat, 1 Jan 1994 12:00:00 +0100 http://epub.ub.uni-muenchen.de/4066/ http://epub.ub.uni-muenchen.de/4066/1/4066.pdf Zatloukal, Kurt; Schneeberger, A.; Berger, M.; Koszik, F.; Schmidt, Walter; Wagner, Ernst; Cotten, Matt; Buschle, M.; Maass, Gerd; Stingl, Georg; Birnstiel, Max L. Zatloukal, Kurt; Schneeberger, A.; Berger, M.; Koszik, F.; Schmidt, Walter; Wagner, Ernst; Cotten, Matt; Buschle, M.; Maass, Gerd; Stingl, Georg und Birnstiel, Max L. (1994): Genetic modification of cells by receptor-mediated adenovirus-augmented gene delivery. A new approach for immunotherapy of cancer. In: Verhandlungen der Deutschen Gesellschaft für Pathologie, Vol. 78: pp. 171-176. Chemie

Sat, 1 Jan 1994 12:00:00 +0100 http://epub.ub.uni-muenchen.de/4067/ http://epub.ub.uni-muenchen.de/4067/1/4067.pdf Cook, Deborah R.; Maxwell, I. H.; Glode, L. M.; Maxwell, F.; Stevens, J. O.; Purner, M. B.; Wagner, Ernst; Curiel, David T.; Curiel, Tyler J. Cook, Deborah R.; Maxwell, I. H.; Glode, L. M.; Maxwell, F.; Stevens, J. O.; Purner, M. B.; Wagner, Ernst; Curiel, David T. und Curiel, Tyler J. (1994): Gene therapy for B-cell lymphoma in a SCID mouse model using an immunoglobulin-regulated diphtheria toxin gene delivered by a novel adenovirus-polylysine conjugate. In: Cancer B

Sat, 1 Jan 1994 12:00:00 +0100 http://epub.ub.uni-muenchen.de/4135/ http://epub.ub.uni-muenchen.de/4135/1/031.pdf Wanner, Klaus Th. Wanner, Klaus Th. (1994): Chiral N-acyliminium ions as new tools in the asymmetric synthesis of CNS-active compounds. In: European Journal of Pharmaceutical Sciences, Vol. 2, Nr. 1-2: pp. 62-64. C

Sat, 1 Jan 1994 12:00:00 +0100 http://epub.ub.uni-muenchen.de/4137/ http://epub.ub.uni-muenchen.de/4137/1/001.pdf Zipse, Hendrik Zipse, Hendrik (1994): Open-Shell Analogs of Closed Shell Reaction Paths. The SRN2' case. In: Journal of the American Chemical Society, Vol. 116, Nr. 23: pp. 10773-10774. Chemie und Pharmazie