title: Chitin synthetase from the yeast and mycelial phases of Blastomyces dermatitidis.
abstract: Chitin synthetase (E.C.2.4.1.16) from mixed membrane fractions of the yeast and mycelial phases of Blastomyces dermatitidis were compared. The behavior of the enzyme from both phases was very similar: N-acetylglucosamine was stimulatory (Km 8.5 mM for yeast and 3.9 mM for mycelium); substrate Michaelis-Menten kinetics were sigmoidal; substrate Km of enzyme from yeast decreased from 3.0 mM at low N-acetylglucosamine (5 mM) levels to 1.4 mM at high (100 mM) levels; substrate Km of enzyme from mycelium was essentially unchanged at 1.4 mM; temperature optimum was 28 degrees C; pH optimum was 7-7.5; Mg+2 optimum was 5-10 mM. The greatest difference was that enzyme from yeast was extracted in a mostly latent form that required trypsin treatment for maximal in vitro activity while enzyme from mycelium was extracted in an active form which was rapidly deactivated by trypsin treatment.
authors.forename: G
authors.initials: G
authors.lastname: Shearer
authors.forename: H W
authors.initials: HW
authors.lastname: Larsh
mesh_terms: D001758:Blastomyces / Q000166:cytology / Q000201:enzymology*; D002687:Chitin Synthase / Q000378:metabolism*; D004789:Enzyme Activation; D005964:Glucosyltransferases / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D013696:Temperature; D014357:Trypsin / Q000378:metabolism
chemical_list: D005964:Glucosyltransferases; D002687:Chitin Synthase; D014357:Trypsin; D008274:Magnesium