P-D-Fucosidase in the Limpet, Patella vulgata

The visceral hump of the limpet, Patella vulgata, is a good source of several glycosidases (Conchie & Levvy, 1957). It has now been observed to contain an enzyme that hydrolyses p-nitrophenyl P-D-fucoside, and it was necessary to determine the relationship between this enzyme and the P-D-galactosidase known to be present in the preparation. Among other methods of discrimination, the actions of the inhibitors, D-galactonolactone and D-fuconolactone, were examined. Levvy, McAllan & Hay (1962) found that the effects of these inhibitors on g-D-galactosidase preparations are largely, if not entirely, dependent on the proportion of the (1-5)-lactones formed in aqueous solutions of the crystalline (1-*4)-lactones. Since this proportion varies rapidly and extensively with the pH, solutions of the lactones were treated immediately before use to give maximum inhibition.