Crystal structure of Dlcaligenes faecalis DA1 D-aminoacylase defines a novel subset of amidohydrolases

• Main Authors: Sheng-Chia Chen, 陳勝嘉
• Other Authors: Shwu - Huey Liaw
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/34245313600087742961

碩士 === 國立陽明大學 === 生物化學研究所 === 90 === D-aminoacylase is an attractive candidate for commercial production of D-amino acids through its catalysis in the hydrolysis of N-acyl-D-amino acids. Here we report the first D-aminoacylase structure, solved by the Se-SAD method, and refined at 1.5 Å resolution. The protein comprises a catalytic “TIM” (βα)8 barrel and a β domain with the highest structural similarity to urease and cytosine deaminase, suggesting that D-aminoacylases indeed belong to the recently identified amidohydrolase superfamily. Unexpectedly, the enzyme binds two zinc ions with widely different affinities, although only the tightly bound zinc is required for activity. One zinc is tightly coordinated by Cys 96, His 220, and His 250, while the other is loosely ligated by His 67, His 69, and Cys 96. Therefore, D-aminoacylase is a mononuclear enzyme but containing a binuclear active site, and then defined a novel subset. The preferred substrate was modeled into a hydrophobic pocket, revealing the substrate specificity.