Isolation and biochemical characterization of a basic myrosinase from ripe Crambe abyssinica seeds, highly specific for epi-progoitrin.
On the basis of previous studies on the mechanism-based inhibition, activation, and active site structure of myrosinase(s) isolated from Sinapis alba and other cruciferous seeds, crambe myrosinase shows uncommon properties and behavior. For this reason homogeneous crambe myrosinase was isolated and investigated to establish the most important physicochemical features, including kinetic properties determined with the epimers progoitrin (R) and epi-progoitrin (S) as substrates, with and without ascorbate as an activator. The results of this study demonstrate that crambe myrosinase is highly specific for epi-progoitrin due to a better stabilization of the enzyme-substrate complex. This stabilization is caused by additional hydrogen bonding that only epi-progoitrin can set up between its hydroxyl group and a suitable residue in the hydrophobic pocket where the "docking" of the glucosinolates side chain takes place.
Bernardi
Roberta
R
Istituto Sperimentale per le Colture Industriali, Italian Ministry of Agricultural and Forestry Politics, Via di Corticella 133, I-40129 Bologna, Italy.
Finiguerra
Michelina G
MG
Rossi
Alessandro A
AA
Palmieri
Sandro
S
D001205:Ascorbic Acid / Q000494:pharmacology; D031218:Crambe Plant / Q000201:enzymology*; D005961:Glucosinolates / Q000378:metabolism* / Q000493:pharmacokinetics; D006026:Glycoside Hydrolases / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D012639:Seeds / Q000201:enzymology*; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D013696:Temperature
D005961:Glucosinolates; C009048:progoitrin; D006026:Glycoside Hydrolases; C022739:thioglucosidase; D001205:Ascorbic Acid