Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.26 (invertase)
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Culture forms of Leishmania (Leishmania) amazonensis (IFLA/BR/67/PH8) produce an extracellular enzyme that hydrolyzes sucrose molecules into their component monosaccharides. This is important because phlebotomine sand flies, the invertebrate hosts of Leishmania, ingest plant sap or aphid and coccid honeydew rich in sucrose between blood meals and Leishmania promastigotes cannot uptake sucrose. The sucrase was purified and characterized; its molecular weight, estimated by gel filtration chromatography and SDS-PAGE electrophoresis, was about 73 kDa. K(m) and V(max) measured with sucrose as substrate were respectively 4.4 mM and 6.9 mumole glucose.min-1 (mg sucrase)-1, with maximum pH activity at pH 5.5. A series of natural and p-nitrophenyl-derived substrates were assayed, characterizing the enzyme as a highly specific beta-D-fructofuranoside fructohydrolase. When 11 species of Leishmania and 7 genera of trypanosomatids were screened, only the species of the genus Trypanosoma did not produce an enzyme with saccharolytic activity. These data are in agreement with the fact that the latter vectors do not acquire sucrose or raffinose in their meals. Searching for glycolytic enzymes other than sucrase, we found an N-acetyl-beta-D-galactosaminolytic activity. This N-acetyl-galactosaminidase, here described for the first time, might have a role in peritrophic membrane disruption. The importance of sucrase and N-acetyl-beta-D-galactosaminidase in the Leishmania life cycle is discussed.
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PMID:Glycosidases in Leishmania and their importance for Leishmania in phlebotomine sandflies with special reference to purification and characterization of a sucrase. 865 40

The sand fly Phlebotomus papatasi Scopoli, 1786, the vector of Leishmania major Yakimoff et Schokhor, 1914, is found in desert areas where sugars are scarce but also in habitats that abound in sugar sources. The sand flies require sugar meals from plant sources for their energy requirements and to hydrolyze these complex sugars, they need a repertoire of glycosidases. We presumed that there are differences in the levels of glycosidase activities in flies from such habitats and also assumed that they may be instrumental in modulating the flies' susceptibility to L. major infections. Phlebotomus papatasi originating from diverse ecological habitats ranging from an oasis to desert sites were colonized. They were analyzed for weight changes and glycosidase activities before and after feeding on 1M sucrose solution. Oasis flies were smaller than desert flies but took larger sugar meals. Homogenates of these flies hydrolyzed 16 synthetic and 2 natural glycoside substrates to varying degrees. The arid-region flies tended to produce more glycosidase activity than those originating in sugar-rich environments, especially sucrase, alpha- and beta-glucosidase, aalpha-fucosidase, alpha-mannosidase, and alpha- and beta-N-acetylgalactosaminidase. However, chitinolytic enzyme activities and particularly the beta-N-acetylhexosaminidase activity of oasis flies were higher than other flies tested. In comparing the desert flies, there were also significant differences in glycolytic enzyme activities between the spring-line (flowering season) of flies and the autumn-line (end of dry season) flies. A range of saccharide inhibitors was tested to demonstrate the specificity of the enzymes.
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PMID:Glycolytic and chitinolytic activities of Phlebotomus papatasi (Diptera: Psychodidae) from diverse ecological habitats. 1830 72