Trypanosoma evansi Sialidase: Surface Localization, Properties and Hydrolysis of Ghost Red Blood Cells and Brain Cells-Implications in Trypanosomiasis
A membrane-bound sialidase was isolated from blood stream (BS) Trypanosoma evansi partially purified and characterized. The enzyme is a glycosyl phosphatidyl inositol (GPI) membrane anchored protein. It was solubilized from T.evansi cells recovered from infected camel blood by detergent treatment wi...
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Published in | Zeitschrift für Naturforschung C. A journal of biosciences Vol. 58; no. 7; pp. 594 - 601 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
Germany
Verlag der Zeitschrift für Naturforschung
01.08.2003
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Subjects | |
Online Access | Get full text |
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Summary: | A membrane-bound sialidase was isolated from blood stream (BS) Trypanosoma evansi partially purified and characterized. The enzyme is a glycosyl phosphatidyl inositol (GPI) membrane anchored protein. It was solubilized from T.evansi cells recovered from infected camel blood by detergent treatment with Triton CF 54 and partially purified by a series of chromatography steps. The enzyme was optimally active at pH 5.5 and 37 °C. It had a Kᴍ and V
values of 4.8 x 10
ᴍ and 3.75 x 10
mol/min.mg protein with Neu5Acα2, 3lac as substrate respectively. The Kᴍ and V
values with fetuin (4-nitrophenyl-oxamic acid) as substrate were 2.9 x 10
ᴍ and 4.2 \ 10
mol/min.mg protein in the same respect. Kinetic analysis with methly umbelliferyl sialate (MU-Neu5Ac) gave Kᴍ and V
values of 0.17 mᴍ and 0.84 mmol/min.mg protein respectively. The T. evansi SD could hydrolyse internally linked sialic acid residues of the ganglioside GM
, but was inactive towards colomic acid, and Neu5Ac2, 6. lac. When ghost red blood cell (RBC) was used as substrate, it desialylated the RBC in the following order of efficiency; mouse, rat, camel, goat, and dog. Similarly, cerebral cells isolated from BalbC mouse was desialylated by the T. evansi SD.
Inhibition studies using 2-deoxy-2, 3 didehydro-N-acetyl neuraminic acid (NeuAc2, 3en) against MU-Neu5Ac revealed a competitive inhibition pattern with K
of 5.8 μm. The enzyme was also inhibited non-competitively by parahydroxy oxamic acid (pHOA), and competitively by N-ethylmaleimide and N-bromosuccinate with K
values of 25, 42, and 53 μm, respectively. It was activated by Mg
ion and inhibited by Cu
and Zn |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0939-5075 1865-7125 |
DOI: | 10.1515/znc-2003-7-825 |