An initial characterization of the proteolytic enzymes secreted by the adult stage of the human hookworm Necator americanus.
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.
Brown
A
A
Department of Life Sciences, Nottingham Trent University.
Burleigh
J M
JM
Billett
E E
EE
Pritchard
D I
DI
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
D002413:Cations, Divalent; D006454:Hemoglobins; D010455:Peptides; D011480:Protease Inhibitors; D005340:Fibrinogen; D010450:Endopeptidases