Purification and Characterization of a C-S-Lyase from Ramson, the Wild Garlic,Allium ursinum

Abstract

A C-S-lyase preparation from ramson,Allium ursinum L., has been purified to apparent homogeneity. Separation techniques applied were hydrophobic interaction chromatography, anion exchange chromatography, and gel permeation chromatography. A 52-fold purification was obtained. The enzyme could be characterized by a molecular mass of M_r = 150000 with subunits of 50 000. Its isoelectric point was determined to be at 4.7. The pH-optimum for the substrate-dependent turnover was found at 6.0. The temperature optimum was at 35°C. (+)-Alliin as the substrate caused the highest enzymatic reaction velocity. The lowest K_m value was observed with (+)-S-propyl-L-cysteine sulfoxide. Inhibitor constants were elaborated for the deoxy-derivatives of the substrates inserted and, likewise, for related amino acids. The protein was sensitive to low concentrations of hydroxylamine, indicating pyridoxal phosphate as a cofactor. Activation energies were determined for the cleavage of alliin,S-propyl-L-cysteine sulfoxide and S-methyl-L-cysteine sulfoxide, and were found to be in the range of 9 to 13 kJ . mol^-1

Key words

Allium ursinum - Alliaceae - wild garlic - ramson - C-S-lyase - cysteine derivatives