Mechanism and substrate stereochemistry of 2-amino-3-oxobutyrate CoA ligase: implications for 5-aminolevulinate synthase and related enzymes.
نویسندگان
چکیده
The condensation process catalysed by 2-amino-3-oxobutyrate CoA ligase (KBL; also known as 2-amino-3-ketobutyrate ligase) involves the loss of the pro-R hydrogen atom of glycine and occurs with the inversion of stereochemistry; a similar scenario is envisaged for the condensation step of other alpha-oxoamine synthases.
منابع مشابه
2-Amino-3-ketobutyrate CoA ligase of Escherichia coli: stoichiometry of pyridoxal phosphate binding and location of the pyridoxyllysine peptide in the primary structure of the enzyme.
Pure 2-amino-3-ketobutyrate CoA ligase from Escherichia coli, which catalyzes the cleavage/condensation reaction between 2-amino-3-ketobutyrate (the presumed product of the L-threonine dehydrogenase-catalyzed reaction) and glycine + acetyl-CoA, is a dimeric enzyme (Mr = 84,000) that requires pyridoxal 5'-phosphate as coenzyme for catalytic activity. Reduction of the hololigase with tritiated Na...
متن کاملThe 2-oxo acid dehydrogenase complexes: recent advances.
The 2-oxo acid dehydrogenase complexes represent the classic examples of multienzyme complexes, a knowledge of whose structure and function has wide implications for our understanding of macromolecular assembly and organization and of protein structure and function. Each complex consists of multiple copies of three enzymes, termed El, E2 and E3. El is a 2-oxo acid dehydrogenase which has thiami...
متن کاملTwo Arabidopsis genes (IPMS1 and IPMS2) encode isopropylmalate synthase, the branchpoint step in the biosynthesis of leucine.
Heterologous expression of the Arabidopsis (Arabidopsis thaliana) IPMS1 (At1g18500) and IPMS2 (At1g74040) cDNAs in Escherichia coli yields isopropylmalate synthases (IPMSs; EC 2.3.3.13). These enzymes catalyze the first dedicated step in leucine (Leu) biosynthesis, an aldol-type condensation of acetyl-coenzyme A (CoA) and 2-oxoisovalerate yielding isopropylmalate. Most biochemical properties of...
متن کاملMurine erythroid 5-aminolevulinate synthase: Adenosyl-binding site Lys221 modulates substrate binding and catalysis
5-Aminolevulinate synthase (ALAS) catalyzes the initial step of mammalian heme biosynthesis, the condensation between glycine and succinyl-CoA to produce CoA, CO2, and 5-aminolevulinate. The crystal structure of Rhodobacter capsulatus ALAS indicates that the adenosyl moiety of succinyl-CoA is positioned in a mainly hydrophobic pocket, where the ribose group forms a putative hydrogen bond with L...
متن کاملPre-steady-state reaction of 5-aminolevulinate synthase. Evidence for a rate-determining product release.
5-Aminolevulinate synthase (ALAS) is the first enzyme of the heme biosynthetic pathway in non-plant eukaryotes and the alpha-subclass of purple bacteria. The pyridoxal 5'-phosphate cofactor at the active site undergoes changes in absorptive properties during substrate binding and catalysis that have allowed us to study the kinetics of these reactions spectroscopically. Rapid scanning stopped-fl...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Chemical communications
دوره 48 شماره
صفحات -
تاریخ انتشار 2006