A comparative study of the proteolytic enzymes of Trypanosoma brucei, T. equiperdum, T. evansi, T. vivax, Leishmania tarentolae and Crithidia fasciculata |
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Authors: | M J North G H Coombs J D Barry |
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Affiliation: | 1. Department of Biological Science, University of Stirling, Stirling FK9 4LA, Scotland;2. Department of Zoology, University of Glasgow, Glasgow G12 8QQ, Scotland. |
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Abstract: | Four types of proteolytic activity were detected in the bloodstream form of each of the four Trypanosoma species: (i) HPAase, active on hide powder azure and detected on polyacrylamide gels containing denatured haemoglobin; (ii) AZCase, active on azocasein; (iii) type 1, active on the chromogenic peptide N-benzoyl-L-prolyl-L-phenylalanyl-L-arginine p-nitroanilide in the presence of dithiothreitol, and (iv) type 2, active against several nitroanilide derivatives in the absence of dithiothreitol. Studies of the pH optimum, dithiothreitol requirement and inhibitor sensitivities of the proteolytic activities suggested that: (a) HPAase and type 1 activities could be due to the same enzymes, probably a family of cysteine proteinases; (b) AZCase had some characteristics of a cysteine proteinase, but was not identical to HPAase, and (c) type 2 activity could be due to a serine proteinase. Procyclic T. brucei contained relatively low cysteine proteinase activities (HPAase, AZCase and type 1) but high type 2 activity. Their proteolytic enzymes thus were apparently more similar to those in Crithidia fasciculata and Leishmania tarentolae promastigotes than those in T. brucei bloodstream forms. |
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Keywords: | Proteinases Peptide nitroanilides Bz benzoyl Tos tosyl Nan 4-nitroaniline HPA hide powder azure AZC azocasein BS bloodstream LS long slender SS short stumpy DTT dithiothreitol TLCK TPCK PMSF phenylmethylsulphonyl fluoride |
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