1E73

2-F-glucosylated MYROSINASE FROM SINAPIS ALBA with bound L-ascorbate

1E73 の概要

• エントリーDOI: 10.2210/pdb1e73/pdb
• 関連するPDBエントリー: 1E4M 1E6Q 1E6S 1E6X 1E70 1E71 1E72 1MYR 2MYR
• 分子名称: MYROSINASE MA1, ZINC ION, 2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose, ... (11 entities in total)
• 機能のキーワード: hydrolase, family 1 glycosyl hydrolase, glucosinolate, myrosinase, tim barrel, ascorbate, activation, glucosyl enzyme
• 由来する生物種: SINAPIS ALBA (WHITE MUSTARD)
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 62444.37

構造登録者

Burmeister, W.P. (登録日: 2000-08-23, 公開日: 2001-01-05, 最終更新日: 2024-11-20)

主引用文献

Burmeister, W.P.,Cottaz, S.,Rollin, P.,Vasella, A.,Henrissat, B.
High Resolution X-Ray Crystallography Shows that Ascorbate is a Cofactor for Myrosinase and Substitutes for the Function of the Catalytic Base
J.Biol.Chem., 275:39385-, 2000

PubMed Abstract: Myrosinase, an S-glycosidase, hydrolyzes plant anionic 1-thio-beta-d-glucosides (glucosinolates) considered part of the plant defense system. Although O-glycosidases are ubiquitous, myrosinase is the only known S-glycosidase. Its active site is very similar to that of retaining O-glycosidases, but one of the catalytic residues in O-glycosidases, a carboxylate residue functioning as the general base, is replaced by a glutamine residue. Myrosinase is strongly activated by ascorbic acid. Several binary and ternary complexes of myrosinase with different transition state analogues and ascorbic acid have been analyzed at high resolution by x-ray crystallography along with a 2-deoxy-2-fluoro-glucosyl enzyme intermediate. One of the inhibitors, d-gluconhydroximo-1,5-lactam, binds simultaneously with a sulfate ion to form a mimic of the enzyme-substrate complex. Ascorbate binds to a site distinct from the glucose binding site but overlapping with the aglycon binding site, suggesting that activation occurs at the second step of catalysis, i.e. hydrolysis of the glycosyl enzyme. A water molecule is placed perfectly for activation by ascorbate and for nucleophilic attack on the covalently trapped 2-fluoro-glucosyl-moiety. Activation of the hydrolysis of the glucosyl enzyme intermediate is further evidenced by the observation that ascorbate enhances the rate of reactivation of the 2-fluoro-glycosyl enzyme, leading to the conclusion that ascorbic acid substitutes for the catalytic base in myrosinase.

PubMed: 10978344
DOI: 10.1074/JBC.M006796200

実験手法

X-RAY DIFFRACTION (1.5 Å)