Evolutionary alkaline transition in human cytochrome c.
Conformational transitions in cytochrome c (cyt c) are being realized to be responsible for its multi-functions. Among a number of conformational transitions in cyt c, the alkaline transition has attracted much attention. The cDNA of human cyt c is cloned by RT-PCR and a high-effective expression system for human cyt c has been developed in this study. The equilibrium and kinetics of the alkaline transition of human cyt c have been systematically investigated for the first time, and compared with those of yeast and horse cyt c from an evolutionary perspective. The pK(a) value for the alkaline transition of human cyt c is apparently higher than that of yeast and horse. Kinetic studies suggest that it is increasingly difficult for the alkaline transition of cyt c from yeast, horse and human. Molecular modeling of human cyt c shows that the omega loop where the lysine residue is located apparently further away from heme in human cyt c than in yeast iso-1 and horse heart cyt c. These results regarding alkaline conformational transition provide valuable information for understanding the molecular basis for the biological multi-functions of cyt c.
Ying
Tianlei
T
Department of Chemistry & Institutes of Biomedical Sciences, Fudan University, Shanghai, China.
Zhong
Fangfang
F
Xie
Jin
J
Feng
Yanjiao
Y
Wang
Zhong-Hua
ZH
Huang
Zhong-Xian
ZX
Tan
Xiangshi
X
D000818:Animals; D003001:Cloning, Molecular; D045304:Cytochromes c / Q000235:genetics* / Q000378:metabolism*; D017931:DNA Primers / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D019143:Evolution, Molecular; D006736:Horses; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008958:Models, Molecular; D011487:Protein Conformation; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013045:Species Specificity; D015003:Yeasts
D017931:DNA Primers; D018076:DNA, Complementary; D045304:Cytochromes c