A BETA-D-FUCOSIDASE FROM ASCLEPIAS-CURASSAVICA LATEX

A beta-D-fucosidase was isolated from Asclepias curassavica latex by a nion exchange and gel filtration chromatography. The enzyme was purifi ed 136-fold. The enzyme is a monomer and its M(r) is close to 50000. I t shows optimal activity at pH 5.5 and at 50-degrees. The enzyme hydro lyses p-nitrophenyl-beta-D-fucopyranoside with apparent K(m) and V(max ) values of 6.58 mM and 304 mM min-1 mg-1 of protein, respectively, at the optimum pH. p-Nitrophenyl-beta-D-fucopyranoside is the best subst rate. D(+)-fucose acts as competitive inhibitor with a K(i) value of 7 .36 mM at pH 5.5. The hypothesis that beta-D-fucosidase represents an enzymatic marker of laticifer differentiation and of the cell wall deg radation process is discussed.