摘要
经酶动力学分析，丝氨酸－１３９的突变体Ｓ１３９Ａ（丙氨酸１３９）使ＤｍＡＤＨ完全失去催化活性．Ｓ１３９Ｃ（半胱氨酸１３９）和Ｓ１３９Ｔ（苏氨酸１３９）使ＤｍＡＤＨ的催化能力分别下降为野生型的１４．３％和４１．６％（对于丙二醇底物）以及４７％和７６％（对于乙醇底物），而且Ｋｃａｔ／Ｋｍ（Ａｌｃ）和Ｋｃａｔ／Ｋｍ（ＮＡＤ）差异极为显著：对于乙醇，突变体相对于野生型（［ＮＡＤ］不变，改变乙醇浓度）变化不大；而对于ＮＡＤ，突变体相对于野生型（即［乙醇］不变，改变ＮＡＤ浓度）下降到原来的１０％以下．
According to the analysis of enzyme dynamics, mutating ser 139 to alanine (S139A) virtually inactivats DmADH, however, substitutions of cysteine (S139C) and Threonine (S139T) at this position cause decrease to 14.3% and 41.6% (for propan 2 ol) 47% and 76% (for ethanol) respectively. The difference between K cat / K m(Alc) and K cat / K m(NAD) is distinct: for ethanol the substitutions (S139C and S139T) cause only a little decrease (in contrast to the wild type) but for NAD more than 90% decrease.
出处
《上海交通大学学报》
EI
CAS
CSCD
北大核心
1997年第4期77-81,共5页
Journal of Shanghai Jiaotong University
关键词
果蝇
醇脱氢酶
人工定点突变
突变体
酶动力学
drosophila melanogaster alcohol dehydrogenase
site directed mutagenesis
S 139 A
