Abstract
The ability ofTrypanosoma brucei brucei to inhibit trypsin or trypsin-like enzymes in crude midgut homogenates ofGlossina morsitans morsitans was studied in vitro. The isolated parasites caused a concentration-dependent decrease in midgut trypsin activity. Furthermore, trypanosomes lysed by repeated freeze-thawing had a similar effect on trypsin activity. In both cases, the inhibition by either intact or lysed parasites was partial as revealed by Dixon plots. Similarly, trypanosome membrane proteins stoichiometrically inhibited trypsin activity, suggesting that the enzyme interacts specifically with a moiety on the parasite surface. The Km and Ki values obtained in this case were 35 μm and 0.18 mg/ml, respectively. These results suggest that one of the ways in which trypanosomes overcome the hostile tsetse-fly midgut barrier involves the inhibition of enzyme activity.
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References
Barbet AF, McGuire TC (1982) Purification ofTrypanosoma brucei variable surface glycoproteins: analysis of degradation occurring during isolation. Parasitology 85:511–522
Borovsky D, Schlein Y (1988) Quantitative determination of trypsin-like and chymotrypsin-like enzymes in insects. Arch Insect Biochem Physiol 8:249–260
Cheeseman MT, Gooding RH (1985) Proteolytic enzymes from tsetse flies,Glossina morsitans andGlossina palpalis (Diptera: Glossinidae). Insect Biochem 15:677–680
Erlanger BF, Kokowsky N, Cohen WC (1961) The preparation and properties of two new chromogenic substrates of trypsin. Arch Biochem Biophys 95:271–278
Gass RF, Yeates RA (1979) In vitro damage of cultured ookinetes ofPlasmodium gallinaceum by digestive proteases from susceptibleAedes aegypti. Acta Trop (Basel) 36:243–252
Grab DJ, Bwayo JJ (1982) Isopycnic isolation of African trypanosomes on Percoll gradients formed in situ. Acta Trop (Basel) 39:363–366
Hoare CA (1972) The trypanosomes of mammals. Blackwell Scientific, Oxford Edinburgh
Ibrahim EAR, Ingram GA, Molyneux DH (1984) Haemagglutinins and parasite agglutinins in haemolymph and gut ofGlossina. Tropenmed Parasitol 35:151–156
Imbuga MO, Osir EO, Labongo VL, Darji N, Otieno LH (1992) Studies on tsetse midgut factors that induce differentiation of bloodstreamTrypanosoma brucei in vitro. Parasitol Res 78:10–15
Ingram GS, Molyneux DH (1988) Lectins (agglutinins) and lysins in the hemolymph and gut extract of tsetse fly,Glossina fuscipes fuscipes. In: Lectins—biology, biochemistry and clinical biochemistry, vol 6. Sigma Chemical Company, St. Louis, Missouri, pp 63–68
Maudlin I, Welburn SC (1987) Lectin mediated establishment of midgut infections ofTrypanosoma congolense andTrypanosoma brucei inGlossina morsitans. Trop Med Parasitol 38:167–170
Otieno LH, Darji N, Onyango P, Mpanga E (1983) Some observations on factors associated with the development ofTrypanosoma brucei brucei infections inGlossina morsitans morsitans. Acta Trop (Basel) 40:113–120
Stiles JK, Molyneux DH, Wallbanks KR (1989) Effects of gammairradiation on the midgut ultrastructure ofGlossina palpalis subspecies. Radiat Res 118:353–363
Stiles JK, Ingram GA, Wallbanks KR, Molyneux DH, Maudlin I, Welburn S (1990) Identification of midgut trypanolysin and trypanoagglutinin inGlossina palpalis sspp. (Diptera: Glossinidae). Parasitology 10:369–376
Welburn SC, Maudlin I (1989) Lectin signalling of maturation ofTrypanosoma congolense infections on tsetse. Med Vet Entomol 3:141–145
Welburn SC, Maudlin I (1991) Rickettsia-like organisms, puparial temperature and susceptibility to trypanosome infection inGlossina morsitans. Parasitology 102:201–206
Welburn SC, Maudlin I, Ellis DS (1989) Rate of trypanosome killing by lectins in midgut of different species and strains ofGlossina. Med Vet Entomol 3:77–82
Yabu Y, Takayanagi T (1988) Trypsin stimulated transformation ofTrypanosoma brucei gambiense bloodstream forms to procyclic forms in vitro. Parasitol Res 74:501–506
Yeates RA, Steiger S (1981) Ultrastructure damage to in vitro cultured ookinetes ofPlasmodium gallinaceum (Brumpt) by purified proteinases of susceptibleAedes aegyti (L.). Z Parasitenkd 66:93–97
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Imbuga, M.O., Osir, E.O. & Labongo, V.L. Inhibitory effect ofTrypanosoma brucei brucei onGlossina morsitans midgut trypsin in vitro. Parasitol Res 78, 273–276 (1992). https://doi.org/10.1007/BF00937083
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DOI: https://doi.org/10.1007/BF00937083