ABSTRACT
Proteolytic activity was detected in neem (Azadirachta indica) exudate gum when tested with casein and albumin as substrates. The enzyme activity was separated into two fractions by chromatography on TEAE-cellulose after EDTA treatment. Both the enzyme fractions were fairly stable to high temperatures and wide range of pH conditions. The pH optima were found to be around 6·5. Phenylmethyl sulphonylfluoride inhibited the activity of both the fractions. EDTA, ß-mercaptoethanol, tosylamide phenylethylchloromethylketone, tosyllysine chloroimethylketone, p-chloromercuribenzoate and dithiobis-2-nitrobenzoie acid did not affect the activity of the two enzyme fractions. The two fractions had no hydrolytic action on a variety of synthetic substrates tested.
ABSTRACT
The partial removal of tightly bound Ca2+ from dialysed neem (Azadirachta indica) gum, resulted in the release of a basic protein from a highly anionic polysaccharide-protein complex as evidenced by chromatographic studies on TEAEcellulose. Complete removal of Ca2+ caused, in addition, the release of a minor heteropolysaccharide which was found in association with the basic protein. These processes were reversed on the addition of Ca2+. The gum, in addition, contained a protein-rich component accounting for 35% protein and 7·5% total carbohydrate. This component behaved as a distinct entity during ion-exchange chromatography of the native gum solutions, or which were either partially or completely depleted of bound Ca2+.