Improved Purification and Further Characterization of an Isomalto-dextranase from Arthrobacter globiformis T6(Biological Chemistry)

概要

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A highly purified isomalto-dextranase (EC 3.2.1.94) was simply separated from the cell-free culture broth of Arthrobacter globiformis T6 by CM-cellulose column chromatography and characterized further. The purified enzyme was essentially homogeneous on PAGE and SDS-PAGE as well as isoelectric focusing. The enzyme was an acidic protein with pI 5.15. E^<1%>_<1cm> at 280nm was 24.6. The molecular weight of the enzyme was estimated to be about 69,000 by SDS-PAGE. No carbohydrate moiety seemed to be associated with the enzyme protein. The optimum pH and temperature of the enzyme was pH 5.3 and 65℃, respectively. The enzyme was completely stable over the range of pH 3.0〜8.0 at 4℃ for 24 hr, and retained about 90% of its original activity after heating at 60℃ for 10min. Inactivation of the enzyme was found to be partial with 5mM Ag^+, and complete with 5mM Hg^<2+>, Fe^<3+>, KMnO_4 , and NBS. The enzyme split dextran, retaining the α-configuration of the anomeric carbon atoms in the hydrolysis products. The K_m value of the enzyme for dextran was 0.038%. Isomaltitol was a potent competitive inhibitor (K_i=0.79 mM).
社団法人日本農芸化学会の論文
1988-02-23