|
type |
Journal Article |
authors |
Okazaki S, Suzuki A, Mizushima T, Kawano T, Komeda H, Asano Y, Yamane T. |
title |
The novel structure of a pyridoxal 5'-phosphate-dependent fold-type I racemase, alpha-amino-epsilon-caprolactam racemase from Achromobacter obae |
journal |
Biochemistry |
Activity |
5.1.1.15 |
Family |
5.1.1.15 |
sel |
selected |
ui |
19146406 |
year |
(2009) |
volume |
48 |
number |
5 |
pages |
941-50 |
| |
abstract |
Alpha-amino-epsilon-caprolactam (ACL) racemase (ACLR) from Achromobacter obae catalyzes the interconversion of l- and d-ACL. ACLR belongs to the fold-type I group of pyridoxal 5'-phosphate (PLP) dependent enzymes. In this study, the first crystal structures of a fold-type I racemase are solved for the native form and epsilon-caprolactam-complexed form of ACLR at 2.21 and 2.40 A resolution, respectively. Based on the location of epsilon-caprolactam in the complex structure, the substrate-binding site is assigned between Trp49 and Tyr137. The carboxyl group of Asp210 is a reasonable candidate that recognizes the nitrogen atom of a lactam or amide in the substrate. Based on a structural comparison with fold-type III alanine racemase, Tyr137 is potentially the acid/base catalytic residue that is essential for the two-base racemization mechanism. The overall structure of ACLR is similar to that of fold-type I enzymes. A structural comparison with these enzymes explains the different reaction specificities. |
last changed |
2009/05/18 15:31 |
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