Isovaleryl CoA dehydrogenase, an enzyme involved in leucine metabolism, will be isolated from rat liver mitochondria and used to transform stereospecifically labeled (3S)-[4-13C]-isovaleryl CoA to Beta-methylcrotonyl CoA. The results will reveal the stereochemistry of the dehydrogenation reaction. The absolute steric course and stereospecificity of ketopantoate hydroxymethyl-transferase (KHMT), which catalyzes the first step of pantothenic acid and coenzyme A biosynthesis, will be determined, using isolated KHMT in a coupled assay with ketopantoate reductase. The steric course of deoxycytidylate hydroxymethylase, a methylenetetrahydrofolate-dependent enzyme induced by T-even bacteriophages in E. coli, will be determined. The mechanism of 4'-phosphopantothenoyl-L-cysteine decarboxylase, another enzyme involved in the biosynthesis of the important acyl group carrier coenzyme A, will be investigated. In particular, the active site groups responsible for reported inhibitions by pyridoxal phosphate and by carbonyl-reactive reagents will be identified.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM024420-12
Application #
3272287
Study Section
Bio-Organic and Natural Products Chemistry Study Section (BNP)
Project Start
1977-06-01
Project End
1992-03-31
Budget Start
1990-04-01
Budget End
1992-03-31
Support Year
12
Fiscal Year
1990
Total Cost
Indirect Cost
Name
Worcester Foundation for Biomedical Research
Department
Type
DUNS #
City
Shrewsbury
State
MA
Country
United States
Zip Code
01545
Burns, D H; Aberhart, D J (1988) A general coupled spectrophotometric assay for decarboxylases. Anal Biochem 171:339-45
Tanaka, K; O'Shea, J J; Finocchiaro, G et al. (1986) Substrate stereochemistry of 2-methyl-branched-chain acyl-CoA dehydrogenase: elimination of one hydrogen each from (pro-2S)-methyl and alpha-methine of isobutyryl-CoA. Biochim Biophys Acta 873:308-11
Aberhart, D J; Ghoshal, P K; Cotting, J A et al. (1985) Coenzyme A biosynthesis: steric course of 4'-phosphopantothenoyl-L-cysteine decarboxylase. Biochemistry 24:7178-82