1qj5
From Proteopedia
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| - | + | {{STRUCTURE_1qj5| PDB=1qj5 | SCENE= }} | |
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'''CRYSTAL STRUCTURE OF 7,8-DIAMINOPELARGONIC ACID SYNTHASE''' | '''CRYSTAL STRUCTURE OF 7,8-DIAMINOPELARGONIC ACID SYNTHASE''' | ||
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[[Category: Sandmark, J.]] | [[Category: Sandmark, J.]] | ||
[[Category: Schneider, G.]] | [[Category: Schneider, G.]] | ||
| - | [[Category: | + | [[Category: Aminotransferase]] |
| - | [[Category: | + | [[Category: Biotin biosynthesis]] |
| - | [[Category: | + | [[Category: Pyridoxal-5'-phosphate]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 06:20:15 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 03:20, 3 May 2008
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. 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 Sat May 3 06:20:15 2008
