A Simple Purification Procedure for and Further Characterization of a Glucodextranase from Arthrobacter globiformis I42 (Biological Chemistry)

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A highly purified glucodextranase (EC 3.2.1.70) was simply prepared from cell-free culture broth of Arthobacter globiformis I42 by ammonium sulfate fractionation, affinity chromatography on Sephadex G-100 and column chromatography on DEAE-cellulose. The purified enzyme was judged to be essentially homogeneous on PAGE and SDS-PAGE as well as isoelectric focusing. E^<1%>_<1cm> at 280 nm was 18.6. The enzyme is an acidic protein with a pI of 4.31. The molecular weight of the enzyme was estimated to be about 120,000 by SDS-PAGE. The enzyme is rich in alanine and glycine. No carbonydrate moiety seemed to be associated with the enzyme protein. The optimum pH and temperature of the enzyme are pH 6.0 and 45℃ for 24hr, and retained about 40% of its original activity after heating at 60℃ for 10min. Inactivation of the enzyme was found to be partial with 5mM Pb^<2+>, or Zn^<2+>, and complete with 5mM each of Cu^<2+>, Hg^<2+>, Fe^<3+>, KMnO_4 and NBS. The enzyme split dextran or isomaltose to produce β-glucose, indicating that the α-glycosidic linkages in these substrates are inverted. The Km value of the enzyme for dextran is 0.014%. Phenyl α-D-glucoside is a potent competitive inhibitor (Ki=1.69mM).
社団法人日本農芸化学会の論文
1988-09-23