1mgv
From Proteopedia
Crystal Structure of the R391A Mutant of 7,8-Diaminopelargonic Acid Synthase
Overview
7,8-diaminopelargonic acid (DAPA) synthase (EC 2.6.1.62) is a pyridoxal phosphate (PLP)-dependent transaminase that catalyzes the transfer of the alpha-amino group from S-adenosyl-L-methionine (SAM) to 7-keto-8-aminopelargonic acid (KAPA) to form DAPA in the antepenultimate step in the biosynthesis of biotin. The wild-type enzyme has a steady-state kcat value of 0.013 s(-1), and the K(m) values for SAM and KAPA are 150 and <2 microM, respectively. The k(max) and apparent K(m) values for the half-reaction of the PLP form of the enzyme with SAM are 0.016 s(-1) and 300 microM, respectively, while those for the reaction with DAPA are 0.79 s(-1) and 1 microM. The R391A mutant enzyme exhibits near wild-type kinetic parameters in the reaction with SAM, while the apparent K(m) for DAPA is increased 180-fold. The 2.1 A crystal structure of the R391A mutant enzyme shows that the mutation does not significantly alter the structure. These results indicate that the conserved arginine residue is not required for binding the alpha-amino acid SAM, but it is important for recognition of DAPA.
About this Structure
1MGV is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
Reference
The dual-specific active site of 7,8-diaminopelargonic acid synthase and the effect of the R391A mutation., Eliot AC, Sandmark J, Schneider G, Kirsch JF, Biochemistry. 2002 Oct 22;41(42):12582-9. PMID:12379100 Page seeded by OCA on Sat May 3 01:00:16 2008
