title: Purification and specificity of two alpha-glucosidase isoforms of the parasitic protist Trichomonas vaginalis.
abstract: Two isoforms of alpha-glucosidase were purified from the parasitic protist Trichomonas vaginalis. Both consisted of 103 kDa subunits, but differed in pH optimum and substrate specificity. Isoform 1 had a pH optimum around 4.5 and negligible activity on glucose oligomers other than maltose, while isoform 2 with a pH optimum of 5.5 hydrolyzed also such substrates at considerable rates. Neither had activity on glycogen or starch. Isoform 1 had a specific activity for hydrolysis of maltose of 30 U/mg protein and isoform 2 101 U/mg protein. The Km values were 0.4 mM and 2.0 mM, respectively. Isoform 2 probably corresponds to the activity detected on the cell surface.
authors.affiliation: The Rockefeller University, New York, New York 10021, USA.
authors.forename: B H
authors.initials: BH
authors.lastname: Ter Kuile
authors.forename: I
authors.initials: I
authors.lastname: Hrdý
authors.forename: L B
authors.initials: LB
authors.lastname: Sánchez
authors.forename: M
authors.initials: M
authors.lastname: Müller
mesh_terms: D000818:Animals; D006863:Hydrogen-Ion Concentration; D007527:Isoenzymes; D008320:Maltose / Q000378:metabolism*; D013379:Substrate Specificity; D014246:Trichomonas vaginalis / Q000201:enzymology*; D000520:alpha-Glucosidases / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D007527:Isoenzymes; D008320:Maltose; D000520:alpha-Glucosidases