title: An initial characterization of the proteolytic enzymes secreted by the adult stage of the human hookworm Necator americanus.
abstract: The proteolytic activities present in adult Necator americanus excretory-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.
authors.affiliation: Department of Life Sciences, Nottingham Trent University.
authors.forename: A
authors.initials: A
authors.lastname: Brown
authors.forename: J M
authors.initials: JM
authors.lastname: Burleigh
authors.forename: E E
authors.initials: EE
authors.lastname: Billett
authors.forename: D I
authors.initials: DI
authors.lastname: Pritchard
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002413:Cations, Divalent / Q000494:pharmacology; D006224:Cricetinae; D010450:Endopeptidases / Q000187:drug effects / Q000378:metabolism*; D005340:Fibrinogen / Q000378:metabolism; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D017221:Necator americanus / Q000201:enzymology* / Q000254:growth & development; D010455:Peptides / Q000378:metabolism; D011480:Protease Inhibitors / Q000494:pharmacology
chemical_list: D002413:Cations, Divalent; D006454:Hemoglobins; D010455:Peptides; D011480:Protease Inhibitors; D005340:Fibrinogen; D010450:Endopeptidases