Synthesis of 13C-labeled γ-hydroxybutyrates for EPR studies with 4-hydroxybutyryl-CoA dehydratase
摘要:
4-Hydroxybutyryl-CoA dehydratase from Clostridium aminobutyricum catalyses the reversible dehydration of its substrate 4-hydroxybutyryl-CoA (4-HB-CoA) to crotonyl CoA. The enzyme contains one [4Fe-4S](2+) cluster and one flavin adenine dinucleotide (FAD) molecule per homotetramer. Incubation of the enzyme with its substrate under equilibrium conditions followed by freezing at 77 K induced the EPR-spectrum of a neutral flavin semiquinone (g = 2.005, linewidth 2.1 mT), while at 10 K additional signals were detected. In an attempt to characterize these signals, 4-HB-CoA molecules specifically labeled with C-13 have been synthesized. This was achieved via C-13-labeled gamma-butyrolactones, which were obtained from C-13-labeled bromoacetic acids by efficient synthetic routes. Incubation of the C-13-labeled 4-hydroxybutyrate-CoA molecules with 4-hydroxybutyryi-CoA dehydratase did not lead to marked broadening of the signals.(C) 2004 Elsevier Inc. All rights reserved.
Synthesis of 13C-labeled γ-hydroxybutyrates for EPR studies with 4-hydroxybutyryl-CoA dehydratase
摘要:
4-Hydroxybutyryl-CoA dehydratase from Clostridium aminobutyricum catalyses the reversible dehydration of its substrate 4-hydroxybutyryl-CoA (4-HB-CoA) to crotonyl CoA. The enzyme contains one [4Fe-4S](2+) cluster and one flavin adenine dinucleotide (FAD) molecule per homotetramer. Incubation of the enzyme with its substrate under equilibrium conditions followed by freezing at 77 K induced the EPR-spectrum of a neutral flavin semiquinone (g = 2.005, linewidth 2.1 mT), while at 10 K additional signals were detected. In an attempt to characterize these signals, 4-HB-CoA molecules specifically labeled with C-13 have been synthesized. This was achieved via C-13-labeled gamma-butyrolactones, which were obtained from C-13-labeled bromoacetic acids by efficient synthetic routes. Incubation of the C-13-labeled 4-hydroxybutyrate-CoA molecules with 4-hydroxybutyryi-CoA dehydratase did not lead to marked broadening of the signals.(C) 2004 Elsevier Inc. All rights reserved.
A synthetic scheme has been developed to prepare methylmethacrylate specifically 13C-labelled at all different positions and in any combination of positions, from simple, commercially available starting materials. According to this scheme methyl (1-13C)- and methyl (2-13C)methacrylate (1a and 1b) have been prepared with high label incorporation (99%).
Regioselective synthesis of 13C1-labeled 2-deoxyribonolactones
作者:Michael P Hayes、Paul J Hatala、Brian A Sherer、Xiaohong Tong、Nilo Zanatta、Philip N Borer、James Kallmerten
DOI:10.1016/s0040-4020(00)01148-0
日期:2001.2
Syntheses of the five regioselectively C-13(1)-labeled 5-O-benzyl-2-deoxyribonolactones are described. C-13(1)-Labeled deoxyribonolactones were prepared by addition of KCN to epoxides 7 and subsequent lactonization of the resulting nitriles. Integration of the independent schemes leading to the five isotopomers of 9 results in an efficient and cost effective preparation of labeled mixtures of C-13 mono-labeled deoxyribonolactones. These mixtures are the pivotal intermediates in the preparation of 'population labeled' C-13-labeled nucleoside phosphoramidites for solid-phase oligonucleotide synthesis. (C) 2001 Elsevier Science Ltd. All rights reserved.
Biosynthesis of virginiae butanolide A, a butyrolactone autoregulator from Streptomyces
Virginiae butanolide A (VB A) (3) is one of the virginiamycin-inducing factors from Streptomyces virginiae and has a unique 2,3-disubstituted butanolide skeleton which is common to other signal molecules in Streptomyces. The biosynthesis of 3 in Streptomyces antibioticus, a high producer of 3, was studied by experiments with labeled precursors. C-13 and H-2 NMR results as well as CI-MS analyses of dibenzoate samples indicated that the probable biosynthetic pathway to 3 involved coupling between a beta-keto acid derivative and a C3 unit from glycerol, such as dihydroxyacetone or a derivative.