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Enhancement of Aminoacylase Activity by Sodium Citrate
作者姓名:于范利  曹志方  李森  周海梦
作者单位:YU Fanli,CAO Zhifang,LI Sen,ZHOU Haimeng Department of Biological Sciences and Biotechnology,Tsinghua University,Beijing 100084,China
摘    要:IntroductionEnzyme activation is a common phenomenon inbiological studies. Many experiments havesuggested that enzyme activation is caused by theconformational change of the enzyme activesites14 ] . Other papers have showed that theenhancement of enzyme activity is associated withsecondary or tertiary structural changes5] .This study analyses aminoacylase (N-acylamino acid amidohydrolase,EC3 .5 .1 .1 4) ,adimeric protein,consisting of two identicalsubunits each with an active site. The zin…


Enhancement of Aminoacylase Activity by Sodium Citrate
YU Fanli,CAO Zhifang,LI Sen,ZHOU Haimeng.Enhancement of Aminoacylase Activity by Sodium Citrate[J].Tsinghua Science and Technology,2001(5).
Authors:YU Fanli  CAO Zhifang  LI Sen  ZHOU Haimeng
Institution:YU Fanli,CAO Zhifang,LI Sen,ZHOU Haimeng Department of Biological Sciences and Biotechnology,Tsinghua University,Beijing 100084,China
Abstract:Kidney and other tissues of animals and humans have a high concentration of citrate which is an important intermediate substance in the citrate cycle. Citrate may play an important physiological role in metabolism. In this paper, we studied the interaction of the sodium salt of citrate with aminoacylase which is an important enzyme in metabolism and found sodium citrate can enhance the activity of aminoacylase.The maximum enzyme activity induced by sodium citrate increased approximately 3 folds over the enzyme activity without sodium citrate. The initial reaction rates (V) for different concentrations of sodium citrate were obtained, showing that sodium citrate is a non competitive activator. The result of the ANS binding fluorescence measurements for aminoacylase indicated that increasing sodium citrate concentrations markedly increased the ANS binding fluorescence with a blue shift of the emission spectra peak. This suggests the formation of more hydrophobic regions. Aggregates formed quickly when aminoacylase was incubated with sodium citrate (0.3 mol/L) and guanidinium chloride (03.5 mol/L). Aminoacylase lost enzyme activity in the guanidinium chloride more quickly in the presence of sodium citrate than in the absence of sodium citrate. The intrinsic fluorescence emission intensity decreased more quickly and the red shift of the emission spectra peak was larger than that without sodium citrate.
Keywords:aminoacylase  sodium citrate  activation  denaturation  unfolding
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