title: The interaction of L-ascorbic acid with the active center of myrosinase.
abstract: Only L-ascorbic acid activated plant myrosinase (thioglucoside glucohydrolase, EC 3.2.3.1), whereas ascorbic acid analogs did not. The enzyme protein was conformationally changed by the addition of L-ascorbic acid to the spectrophotometric analysis, approx. 1.5 amino residues appeared on the surface of the enzyme and about 2.3 tryptophan residues were buried in the molecule when 1 mM L-ascorbic acid was added. Optimum temperature for the myrosinase activity was approx. 55 degrees C without L-ascorbic acid, but with L-ascorbic acid it was about 35 degrees C; that for beta-glucosidase activity was the same (55 degrees C) with or without L-ascorbic acid. The effect of chemical modification of the functional groups of myrosinase on the interaction of L-ascorbic acid was investigated and the interaction of L-ascorbic acid with the active center of the enzyme is proposed.
mesh_terms: D015077:2-Hydroxy-5-nitrobenzyl Bromide / Q000494:pharmacology; D001205:Ascorbic Acid / Q000031:analogs & derivatives / Q000494:pharmacology*; D001665:Binding Sites; D006026:Glycoside Hydrolases / Q000378:metabolism*; D008626:Mercuribenzoates / Q000494:pharmacology; D010944:Plants / Q000201:enzymology; D011487:Protein Conformation; D013696:Temperature; D013863:Thioglucosides; D014326:Tropanes / Q000494:pharmacology; D001617:beta-Glucosidase / Q000378:metabolism
chemical_list: D008626:Mercuribenzoates; D013863:Thioglucosides; D014326:Tropanes; D015077:2-Hydroxy-5-nitrobenzyl Bromide; D006026:Glycoside Hydrolases; C022739:thioglucosidase; D001617:beta-Glucosidase; D001205:Ascorbic Acid