title: Identification and characterization of the cysteine and serine proteinases of the trematode, Haplometra cylindracea and determination of their haemoglobinase activity.
abstract: The excreted/secreted proteinases of Haplometra cylindracea maintained in vitro, were found to hydrolyse the fluorogenic substrates, Z-ArgArg-NHMec and Z-PheArg-NHMec. This activity was shown to be typically that of cysteine proteinases, as turn-over of both substrates could be blocked by pre-incubation with peptidyl diazomethyl ketones. The biotinylated affinity reagent, biotin-Phe Ala-DMK, used in combination with Z-PheTyr(OBut)-DMK, was employed for the labelling and characterization of these cysteine proteinase activities. Three cathepsin B-like species were detected, with molecular weights of 48, 22-23 and 14 kDa, together with a cathepsin L-like enzyme, with a molecular weight of 55 kDa. The proteinases were also found to have hydrolytic activity towards the substrate, Z-GlyGlyArg-NHMec, which could be blocked by pre-incubation with either of the serine proteinase-selective reagents, Z-Argp(OPh)2 or biotin-Lysp(OPh)2, showing the activity to be trypsin-like. Using the biotinylated affinity label to characterize the trypsin-like enzymes revealed two molecular species with molecular weights of 20 and 24 kDa.
authors.affiliation: Division of Biochemistry, Medical Biology Centre, The Queen's University of Belfast, Northern Ireland, UK.
authors.forename: S J
authors.initials: SJ
authors.lastname: Hawthorne
authors.forename: D W
authors.initials: DW
authors.lastname: Halton
authors.forename: B
authors.initials: B
authors.lastname: Walker
mesh_terms: D000345:Affinity Labels; D000595:Amino Acid Sequence; D000818:Animals; D003546:Cysteine Endopeptidases / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D015801:Helminth Proteins; D006868:Hydrolysis; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009842:Oligopeptides / Q000737:chemistry; D011896:Rana temporaria / Q000469:parasitology; D012697:Serine Endopeptidases / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D013379:Substrate Specificity; D014200:Trematoda / Q000201:enzymology*
chemical_list: D000345:Affinity Labels; D015801:Helminth Proteins; D009842:Oligopeptides; D012697:Serine Endopeptidases; D003546:Cysteine Endopeptidases