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Gómez-Balderas R Raffa DF Rickard GA Brunelle P Rauk A 《The journal of physical chemistry. A》2005,109(24):5498-5508
A systematic study of the binding motifs of Cu(II) and Cu(I) to a methionine model peptide, namely, N-formylmethioninamide 1, has been carried out by quantum chemical computations. Geometries of the coordination modes obtained at the B3LYP/6-31G(d) level of theory are discussed in the context of copper coordination by the peptide backbone and the S atom of a methionine residue in peptides with special emphasis on Met35 of the amyloid-beta peptide (Abeta) of Alzheimer's disease. The relative binding free energies in the gas phase, DeltaG(g), are calculated at the B3LYP/6-311+G(2df,2p)//B3LYP/6-31G(d) level of theory, and the solvation affects are included by means of the COSMO model to obtain the relative binding energies in solution, DeltaG(aq). A free energy of binding, DeltaG(aq) = -19.4 kJ mol(-1), relative to aqueous Cu(II) and the free peptide is found for the most stable Cu(II)/Met complex, 12. The most stable Cu(I)/Met complex, 23, is bound by -15.6 kJ mol(-1) relative to the separated species. The reduction potential relative to the standard hydrogen electrode is estimated to be E degrees (12/23) = 0.41 V. On the basis of these results, the participation of Met35 as a low affinity binding site of Cu(II) in Abeta, and its role in the redox chemistry underlying Alzheimer's disease is discussed. 相似文献
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Duilio Arigoni David E. Cane Beat Müller Christoph Tamm 《Helvetica chimica acta》1973,56(8):2946-2949
In the course of the biosynthesis of verrucarol ( 3 ) from farnesyl pyrophosphate in Myrothecium roridum, strain S 1135, a hydride shift occurs from the central double bond of the precursor to C(2) of the product. 相似文献
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Pasquali C Vilbois F Curchod ML Hooft van Huijsduijnen R Arigoni F 《Electrophoresis》2000,21(16):3357-3368
Studies of protein-protein interactions have proved to be a useful approach to link proteins of unknown function to known cellular processes. In this study we have combined several existing methods to attempt the comprehensive identification of substrates for poorly characterized human protein tyrosine phosphatases (PTPs). We took advantage of so-called "substrate trapping" mutants, a procedure originally described by Flint et al. (Proc. Natl. Acad. Sci. USA 1997, 94, 1680-1685) to identify binding partners of cloned PTPs. This procedure was adapted to a proteome-wide approach to probe for candidate substrates in cellular extracts that were separated by two-dimensional (2-D) gel electrophoresis and blotted onto membranes. Protein-protein interactions were revealed by far-Western immunoblotting and positive binding proteins were subsequently identified from silver-stained gels using tandem mass spectrometry. With this method we were able to identify possible substrates for PTPs without using any radio-labeled cDNA or protein probes and showed that they corresponded to tyrosine phosphorylated proteins. We believe that this method could be generally applied to identify possible protein-protein interactions. 相似文献
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Fritz Kunz Jnos Rtey Duilio Arigoni Lin Tsai Thressa C. Stadtman 《Helvetica chimica acta》1978,61(3):1139-1145
Absolute configuration of the 3,5-diaminohexanoic acid produced in the β-lysine mutase reaction The (3S, 5S)-configuration of the 3,5-diaminohexanoic acid 3 produced by the coenzyme-B12-dependent β-lysine mutase from Clostridium sticklandii has been determined by two different methods: by comparison of the 1H-NMR.-spectrum of its δ-lactam with that of synthetic (±)-cis-and (±)-trans-4-amino-6-methyl-piperidones ( 1 and 2 ) and by chemical correlation with (+)-(6S)-6-methyl-piperidone-2 ( 9 ). 相似文献
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Jnos Rtey Fritz Kunz Duilio Arigoni Thressa C. Stadtman 《Helvetica chimica acta》1978,61(8):2989-2998
Investigations on the β-lysine mutase reaction: Mechanism and steric course The steric course and some mechanistic aspects of the coenzyme-B12-dependent β-lysine-mutase reaction, in which (3 S)-β-lysine is converted to (3 S, 5 S)-3, 5-diaminohexanoate, have been investigated by means of tritium labelling. The reaction involves migration of an hydrogen atom from C(5) of the substrate to C(5′) of coenzyme B12 and back-transfer to C(6) of the product. In the presence of [5′-3H]-coenzyme B12 the enzyme catalyzes the exchange of label between the cofactor and one of the diastereotopic H-atoms at C(5) of the substrate. The exchangeable hydrogen atom is identical with the one specifically involved in the migration reaction. Degradation of the tritiated β-lysine obtained in such experiments yielded a sample of tritiated succinic acid which was shown in an enzymic assay involving partial oxidation with succinate dehydrogenase, to possess the (S)-configuration. Thus, the overall substitution at C(5) occurs with inversion of configuration. 相似文献
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W O Godtfredsen W von Daehne S Vangedal A Marquet D Arigoni A Melera 《Tetrahedron》1965,21(12):3505-3530
Evidence is presented which shows that the antibiotic fusidic acid possesses the relative and absolute stereochemistry depicted in 2. The biogenetic implications of this result are briefly discussed. 相似文献
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