This old version of Proteopedia is provided for student assignments while the new version is undergoing repairs. Content and edits done in this old version of Proteopedia after March 1, 2026 will eventually be lost when it is retired in about June of 2026.
Apply for new accounts at the new Proteopedia. Your logins will work in both the old and new versions.
1qj5
From Proteopedia
|
CRYSTAL STRUCTURE OF 7,8-DIAMINOPELARGONIC ACID SYNTHASE
Overview
The three-dimensional structure of diaminopelargonic acid synthase, a, vitamin B6-dependent enzyme in the pathway of the biosynthesis of biotin, has been determined to 1.8 A resolution by X-ray crystallography. The, structure was solved by multi-wavelength anomalous diffraction techniques, using a crystal derivatized with mercury ions. The protein model has been, refined to a crystallographic R -value of 17.5% (R -free 22.6%). Each, enzyme subunit consists of two domains, a large domain (residues 50-329), containing a seven-stranded predominantly parallel beta-sheet, surrounded, by alpha-helices, and a small domain comprising residues 1-49 and 330-429., Two subunits, related by a non-crystallographic dyad in the crystals, form, the homodimeric molecule, which contains two equal active sites., Pyridoxal-5'-phosphate is bound in a cleft formed by both domains of one, subunit and the large domain of the second subunit. The cofactor is, anchored to the enzyme by a covalent linkage to the side-chain of the, invariant residue Lys274. The phosphate group interacts with main-chain, nitrogen atoms and the side-chain of Ser113, located at the N terminus of, an alpha-helix. The pyridine nitrogen forms a hydrogen bond to the, side-chain of the invariant residue Asp245. Electron density corresponding, to a metal ion, most likely Na(+), was found in a tight turn at the, surface of the enzyme. Structure analysis reveals that diaminopelargonic, acid synthase belongs to the family of vitamin B6-dependent, aminotransferases with the same fold as originally observed in aspartate, aminotransferase. A multiple structure alignment of enzymes in this family, indicated that they form at least six different subclasses. Striking, differences in the fold of the N-terminal part of the polypeptide chain, are one of the hallmarks of these subclasses. Diaminopelargonic acid, synthase is a member of the aminotransferase subclass III. From the, structure of the non-productive complex of the holoenzyme with the, substrate 7-keto-8-aminopelargonic acid the location of the active site, and residues involved in substrate binding have been identified.
About this Structure
1QJ5 is a Single protein structure of sequence from Escherichia coli with and as ligands. Active as Adenosylmethionine--8-amino-7-oxononanoate transaminase, with EC number 2.6.1.62 Known structural/functional Sites: and . Full crystallographic information is available from OCA.
Reference
Crystal structure of diaminopelargonic acid synthase: evolutionary relationships between pyridoxal-5'-phosphate-dependent enzymes., Kack H, Sandmark J, Gibson K, Schneider G, Lindqvist Y, J Mol Biol. 1999 Aug 27;291(4):857-76. PMID:10452893
Page seeded by OCA on Sun Feb 3 10:00:24 2008
