Vitamin B12, in the form of its coenzyme, is an obligatory cofactor in a series of twelve enzyme catalyzed reactions. The glutamate mutase, methyl- malonyl-CoA mutase and methylitaconate mutase enzymes are of outstanding interest because they catalyze carbon-skeleton rearrangements for which there have been no analogues in organic chemistry. The methylmalonyl-CoA to succinyl-CoA rearrangement is of crucial import in mammalian systems; it is the way the body converts propionate to succinate, leading into the main stream of biochemical metabolism. In this proposal, the mechanism by which these rearrangements occur will be explored using both model and enzymic systems. A new model for the methymalonyl-CoA system has been synthesized with an appended free radical trap to test for the occurrence of radical intermediates. This test will also be applied to the enzyme system. In addition, a new, synthetic malonate binding molecule will be used to study the reversibility of the model rearrangement. In order to facilitate the study of the function and structure of glutamate mutase, the gene will be cloned. Then, with adequate supplies of pure enzyme, mechanistic and structural studies will be initiated. Free radical and carbanion intermediates in the glutamate-methylaspartate rearrangement will be explored and a very successful Schiff base model will be developed. Surfactant-based models will be examined for their impact on our understanding of some unprecedented free radical migration reactions.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM019906-16
Application #
3269791
Study Section
Metallobiochemistry Study Section (BMT)
Project Start
1978-07-01
Project End
1994-11-30
Budget Start
1992-12-01
Budget End
1993-11-30
Support Year
16
Fiscal Year
1993
Total Cost
Indirect Cost
Name
University of Pittsburgh
Department
Type
Schools of Arts and Sciences
DUNS #
053785812
City
Pittsburgh
State
PA
Country
United States
Zip Code
15213
Choi, G Y; Choi, S C; Galan, A et al. (1990) Vitamin B12S-promoted model rearrangement of methylmalonate to succinate is not a free radical reaction. Proc Natl Acad Sci U S A 87:3174-6