TY - JOUR
T1 - Proteases from Trypanosoma brucei brucei
T2 - Purification, characterisation and interactions with host regulatory molecules
AU - Troeberg, Linda
AU - Pike, Robert N.
AU - Morty, Rory E.
AU - Berry, Ronald K.
AU - Coetzer, Theresa H.T.
AU - Lonsdale-Eccles, John D.
PY - 1996/1/1
Y1 - 1996/1/1
N2 - African trypanosomes contain proteases that may be released into the bloodstream of their infected hosts. This paper describes a novel, combined isolation of a cysteine proteinase (called trypanopain-Tb) and a serine oligopeptidase (which we call oligopeptidase-Tb) from Trypanosoma brucei brucei, as well as a comparison of the activities of these two enzymes against several host regulatory molecules. The enzymes differed in various respects. Firstly, purified trypanopain-Tb was shown to readily cleave proteins such as gelatin maximally at acidic pH. In contrast, oligopeptidase- Tb, which is optimally active at alkaline pH, did not hydrolyase proteins larger than 4 kDa. However, it readily hydrolysed various polypeptides, including neurotensin and atrial natriuretic factor. The interaction of the two enzymes with mammalian protease inhibitors also differed. Cystatins and α2-macroglobulin effectively inhibited trypanopain-Tb, with the K(i) values for cystatin C and low-molecular-mass kininogen (≃10-11 M) predicting that trypanopain-Tb is likely to be effectively controlled by these inhibitors if released into the host bloodstream. In contrast, oligopeptidase-Tb was not inhibited by serpins or α2-macroglobulin, suggesting that it may remain active if released into the host bloodstream. In support of these in vitro results, the blood of trypanosome-infected rats displayed no trypanopain-Tb-like activity, but exhibited high oligopeptidase- Tb-like activity. Thus, while trypanopain-Tb seems likely to be confined to an intracellular role within the parasite, oligopeptidase-Tb has the potential to remain active in the host bloodstream and so contribute directly to pathogenesis.
AB - African trypanosomes contain proteases that may be released into the bloodstream of their infected hosts. This paper describes a novel, combined isolation of a cysteine proteinase (called trypanopain-Tb) and a serine oligopeptidase (which we call oligopeptidase-Tb) from Trypanosoma brucei brucei, as well as a comparison of the activities of these two enzymes against several host regulatory molecules. The enzymes differed in various respects. Firstly, purified trypanopain-Tb was shown to readily cleave proteins such as gelatin maximally at acidic pH. In contrast, oligopeptidase- Tb, which is optimally active at alkaline pH, did not hydrolyase proteins larger than 4 kDa. However, it readily hydrolysed various polypeptides, including neurotensin and atrial natriuretic factor. The interaction of the two enzymes with mammalian protease inhibitors also differed. Cystatins and α2-macroglobulin effectively inhibited trypanopain-Tb, with the K(i) values for cystatin C and low-molecular-mass kininogen (≃10-11 M) predicting that trypanopain-Tb is likely to be effectively controlled by these inhibitors if released into the host bloodstream. In contrast, oligopeptidase-Tb was not inhibited by serpins or α2-macroglobulin, suggesting that it may remain active if released into the host bloodstream. In support of these in vitro results, the blood of trypanosome-infected rats displayed no trypanopain-Tb-like activity, but exhibited high oligopeptidase- Tb-like activity. Thus, while trypanopain-Tb seems likely to be confined to an intracellular role within the parasite, oligopeptidase-Tb has the potential to remain active in the host bloodstream and so contribute directly to pathogenesis.
KW - cystatin
KW - cysteine proteinase
KW - oligopeptidase
KW - Trypanosoma brucei
UR - http://www.scopus.com/inward/record.url?scp=0030017685&partnerID=8YFLogxK
U2 - 10.1111/j.1432-1033.1996.0728w.x
DO - 10.1111/j.1432-1033.1996.0728w.x
M3 - Article
C2 - 8706674
AN - SCOPUS:0030017685
SN - 0014-2956
VL - 238
SP - 728
EP - 736
JO - European Journal of Biochemistry
JF - European Journal of Biochemistry
IS - 3
ER -