An initial characterization of the proteolytic enzymes secreted by the adult stage of the human hookwormNecator americanus

Publisher Website
Google Scholar
Abstract
SUMMARY: The proteolytic activities present in adultNecator americanusexcretory–secretory products have been assessed using biologically relevant, naturally occurring substrates (haemoglobin and fibrinogen) and a number of synthetic fluorogenic and chromogenic substrates. One broad peak of activity was observed against haemoglobin in the pH range 5 to 7, with maximum activity at pH 6·6, while fibrinogenolytic activity was shown to be greater at pH 3·5. Inhibition studies against haemoglobin, fibrinogen and synthetic substrates using a battery of appropriate protease inhibitors indicated the presence of a mixture of aspartyl, cysteinyl and serine proteases. Metal ion (Ca2+, Zn2+and Fe2+) stimulation was demonstrated, with stimulation by Zn2+being the most marked. These results are discussed in the context of recent developments in the field of parasite proteolytic enzymes, where they have been suggested as targets for immuno- and chemotherapy.