title: Characterization of two trehalases in baker's yeast.
abstract: Trehalase activities at pH 5 (not inhibited by EDTA) and pH 7 (inhibited by EDTA) were present in the soluble fraction of disintegrated commercial baker's yeast. The pH 5 activity binds strongly to concanavalin A, is only partially salted out by saturated (NH4)2SO4, has an apparent Mr of 215000 (by gel filtration) and is an acidic protein. It has a Km of 1.4 mM, a broad pH optimum (at 40 mM-trehalose) between pH 4 and 5, and is activated by about 30% by 20-300 mM neutral salts such as KCl, NaNO3 and MnCl2. The enzyme is strongly inhibited by acetic acid/acetate buffers, with a Ki of about 15 mM-acetic acid. The pH 7 activity does not bind to concanavalin A, is salted out at 20-32% (w/v) (NH4)2SO4 and has an Mr of 170000 (by gel filtration). It is absolutely dependent on Ca2+ or Mn2+ ions (Mg2+ is ineffective) and strongly inhibited by neutral salts in the 20-100 mM range. It can be activated by treatment with MgATP in the presence of cyclic AMP. Activation decreases, but does not abolish, the Ca2+ requirement, and does not change the Km for trehalose (5.7 mM) or shift the sharp pH optimum at pH 6.7 (at 40 mM-trehalose).
mesh_terms: D002413:Cations, Divalent / Q000494:pharmacology; D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D004492:Edetic Acid / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000302:isolation & purification; D007700:Kinetics; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D013379:Substrate Specificity; D014198:Trehalase / Q000037:antagonists & inhibitors / Q000302:isolation & purification
chemical_list: D002413:Cations, Divalent; D007527:Isoenzymes; D004492:Edetic Acid; D014198:Trehalase