Effects of Ca2+ on the activity and thermal stability of γ-glutamyltranspeptidase from Bacillus subtilis

Xi Wen Song, Yan Ling Xiao, Zhi Zhou, Zhong Yao, Hong Xu, Ping Wei

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

The γ-glutamyltranspeptidase (GGT) can be used to synthesize the new γ-glutamyl compounds by using γ-glutamyl compounds as acyl donor substrate and transfering their γ-glutamyl moieties to acceptor substrate. However the GGT has the defect of having low thermal stability. In order to improve its poor thermal stability, the method of adding Ca2+ was adopted in this study, and the effects of added Ca2+ on the activity and thermal stability of GGT obtained from the fermentation of Bacillus subtilis were investigated. It was found that the thermal stability of GGT is greatly improved after it was treated with CaCl2 of 4 mmol · L-1 at 37°C for 30 min. As the GGT working temperature increases, the effect of Ca2+ treatment on increasing the thermal stability of GGT is more obvious. The kinetic constants of acylation reaction using GGT treated with Ca2+ were determined as Km=0.23 mmol · L-1, Vmax=0.015 mmol · L-1 · min-1 and the activation energy Ea=10.50 kJ · mol-1. The above Km and Ea values are significantly lower than those of acylation reaction using GGT without treated with Ca2+. The inactivation energy Ed of inactivation reaction for GGT was also calculated and it was found to be 60.47 kJ · mol-1, which is much higher than that of the GGT without treated with Ca2+ (50.42 kJ · mol-1). The study comes to the conclusion that the activity and thermal stability of GGT are obviously improved after treating it with Ca2+, and the Ca2+ could reduce the deactivation of GGT.

Original languageEnglish
Pages (from-to)85-90
Number of pages6
JournalGao Xiao Hua Xue Gong Cheng Xue Bao/Journal of Chemical Engineering of Chinese Universities
Volume25
Issue number1
StatePublished - Feb 2011

Keywords

  • Activation energy
  • Ca
  • Kinetics
  • Thermal stability
  • γ-glutamyltranspeptidase

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