1e73 | pdb_00001e73

2-F-GLUCOSYLATED MYROSINASE FROM SINAPIS ALBA WITH BOUND L-ASCORBATE

spinqualitylabelsall models 1e73, resolution 1.50Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1e73 is a 1 chain structure with sequence from Sinapis alba. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: ASC, BMA, G2F, GOL, NAG, SO4, ZN, FUC, MAN, XYP Related: 1e4m, 1e6q, 1e6s, 1e6x, 1e70, 1e71, 1e72, 1myr, 2myr Activity: Thioglucosidase, with EC number 3.2.1.147 Resources: FirstGlance, OCA, RCSB, PDBsum Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed 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. High resolution X-ray crystallography shows that ascorbate is a cofactor for myrosinase and substitutes for the function of the catalytic base.,Burmeister WP, Cottaz S, Rollin P, Vasella A, Henrissat B J Biol Chem. 2000 Dec 15;275(50):39385-93. PMID:10978344 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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