Mutation-induced perturbation of the cytochrome c alkaline transition.
Mutation-induced perturbation of the cytochrome c alkaline transition.
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突变诱导的细胞色素 c 碱性转变的扰动。
DOI：
10.1021/bi00434a006
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发表时间：
1989
期刊：
影响因子：
2.9
通讯作者：
Mauk,AG
中科院分区：
文献类型：
--
作者：
Pearce,LL;Gärtner,AL;Smith,M;Mauk,AG
不列颠哥伦比亚省，温哥华，不列颠哥伦比亚省V6 T 1 W5，加拿大，生物化学系，1988年7月26日接收; 1988年10月12日接收修订版摘要：通过对一个突变型酵母iso-1- 1的pH滴定，研究了Phe-82残基对细胞色素c碱性异构化的影响。细胞色素C，其中在该位置的残基的身份已经改变。Met-80血红素铁配体交换的p^ fa通过pH滴定法测定，其中监测S-*· Fe电荷转移带（695 nm），发现野生型为8.5，Ser-82为7.7，Gly-82为7.7，Leu-82为7.2，Ile-82为7.2。pH跳跃实验[Davis et al.（1974）J.Biol.Chem.249，2624]确定了在位置82处的取代通过降低滴定基团的pKa多达1.4pK单位来影响碱性异构化;对于Ser-82和Gly-82变体，对配体交换平衡也存在小的影响。基于这些发现，我们得出结论，Phe-82在野生型蛋白中的一个关键作用是稳定天然血红素结合环境。
Department of Biochemistry, University of British Columbia, Vancouver, British Columbia V6T 1W5, Canada Received July 26, 1988; Revised Manuscript Received October 12, 1988 abstract: The possible influence of residue Phe-82 in the cytochrome c alkaline isomerization has been evaluated by spectrophotometricpH titrations of a family of mutant yeast iso-1-cytochromes c in which the identity of the residue at this position has been varied. The p^ fa for the exchange of the Met-80 heme iron ligand was determined from pH titrations in which the S—*· Fe charge-transfer band (695 nm) was monitored and was found to be 8.5 for the wild type, 7.7 for Ser-82, 7.7 for Gly-82, 7.2 for Leu-82, and 7.2 for Ile-82. pH-jump experiments [Davis et al.(1974) J. Biol. Chem. 249, 2624] established that substitutions at position 82 affect the alkaline isomerization by lowering the pKa of the titrating group by as much as 1.4 pK units; for the Ser-82 and Gly-82 variants, there is also a small effect on the for the ligand exchange equilibrium. On the basis of these findings, we conclude that one critical role for Phe-82 in the wild-type protein is stabilization of the nativeheme binding environment.