2ZPR

Crystal structure of anionic trypsin isoform 2 from chum salmon

2ZPR の概要

• エントリーDOI: 10.2210/pdb2zpr/pdb
• 関連するPDBエントリー: 2ZPQ 2ZPS
• 分子名称: Anionic trypsin, CALCIUM ION, BENZAMIDINE, ... (4 entities in total)
• 機能のキーワード: serine proteinase, trypsin, hydrolase, protease, serine protease
• 由来する生物種: Oncorhynchus keta (Chum salmon)
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 47817.75

構造登録者

Iyaguchi, D.,Toyota, E. (登録日: 2008-07-28, 公開日: 2009-07-28, 最終更新日: 2024-10-30)

主引用文献

Toyota, E.,Iyaguchi, D.,Sekizaki, H.,Tateyama, M.,Ng, K.K.
A structural comparison of three isoforms of anionic trypsin from chum salmon (Oncorhynchus keta).
Acta Crystallogr.,Sect.D, 65:717-723, 2009

PubMed Abstract: Three anionic salmon trypsin isoforms (CST-1, CST-2 and CST-3) were isolated from the pyloric caeca of chum salmon (Oncorhynchus keta). The order of catalytic efficiency (K(m)/k(cat)) of the isoforms during BAPA hydrolysis was CST-2 > CST-1 > CST-3. In order to find a structural rationalization for the observed difference in catalytic efficiency, the X-ray crystallographic structures of the three isoforms were compared in detail. Some structural differences were observed in the C-terminal alpha-helix, interdomain loop and active-site region. From the results of the detailed comparison, it appears that the structural flexibility of the C-terminal alpha-helix, which interacts with the N-terminal domain, and the substrate-binding pocket in CST-3 are lower than those in CST-1 and CST-2. In addition, the conformation of the catalytic triad (His57, Asp102 and Ser195) differs among the three isoforms. The imidazole N atom of His57 in CST-1 and CST-2 forms a hydrogen bond to the hydroxyl O atom of Ser195, but the distance between the imidazole N atom of His57 and the hydroxyl O atom of Ser195 in CST-3 is too great (3.8 A) for the formation of a hydrogen bond. Thus, the nucleophilicity of the hydroxyl group of Ser195 in CST-3 is weaker than that in CST-1 or CST-2. Furthermore, the electrostatic potential of the substrate-binding pocket in CST-2 is markedly lower than those in CST-1 and CST-3 owing to the negative charges of Asp150, Asp153 and Glu221B that arise from the long-range effect. These results may explain the higher catalytic efficiency of CST-2 compared with CST-1 and CST-3.

PubMed: 19564692
DOI: 10.1107/S0907444909012165

実験手法

X-RAY DIFFRACTION (1.75 Å)