来自环状芽孢杆菌DF 9 R型的环麦芽糊精-葡聚糖转移酶的一些特性

Some properties of a cyclomaltodextrin-glucanotransferase from Bacillus circulans DF 9 R type.

作者信息

Maréchal L R, Rosso A M, Maréchal M A, Krymkiewicz N, Ferrarotti S A

机构信息

Instituto de Investigaciones Bioquímicas Luis F. Leloir Fundación Campomar, Buenos Aires, Argentina.

出版信息

Cell Mol Biol (Noisy-le-grand). 1996 Jul;42(5):659-64.

PMID:8832096

Abstract

The cyclomaltodextrin-glucanotransferase (EC2.4.1.19, CGTase) which was purified to homogeneity from Bacillus circulans strain DF 9, R type, showed a pI of 5.3 determined by disc-isoelectric focusing, a Mw of 78 kDa estimated by SDS-PAGE with a range of pH of optimal enzymatic activity rather large (4.5-7.5). The thermal stability of the enzyme at 55 degrees C was increased 4-5 times when calcium ion (10 to 100 mM) or alpha-cyclodextrins (10 mM) were added to the preincubation mixtures. The alpha: beta: gamma ratio determined by HPLC was about 1:0.9:0.4 and the maximal conversion to cyclodextrins with 5% soluble starch was about 36%.

摘要

从环状芽孢杆菌DF 9型R菌株中纯化至同质的环麦芽糊精-葡聚糖转移酶（EC2.4.1.19，CGT酶），通过圆盘等电聚焦测定其pI为5.3，通过SDS-PAGE估计其Mw为78 kDa，最佳酶活性的pH范围相当宽（4.5 - 7.5）。当向预孵育混合物中加入钙离子（10至100 mM）或α-环糊精（10 mM）时，该酶在55℃的热稳定性提高了4至5倍。通过HPLC测定的α:β:γ比例约为1:0.9:0.4，以5%可溶性淀粉为底物时向环糊精的最大转化率约为36%。