Partially Hydrolyzed Yeast Cytochrome c Obtained by Chymotryptic Digestion

抄録

Cytochrome c of Saccharomyces oviformis M₂ was partially hydrolyzed with chymotrypsin and a new fraction with cytochrome c activity was obtained. The absorption spectra and ultraviolet difference spectra of the chymo-trypsin-digested cytochrome c with and without urea treatment were the same as those of intact cytochrome c. The N-terminal amino acid of this modified cytochrome c was lysine, and the C-terminal amino acid was the same as in ordinary cytochrome c. So it was concluded that the new material was obtained by removal of threonyl-glutamyl-phenylalanine from the N-terminal side of ordinary cyto-chrome c.
The interconversion of the sulf hydryl and disulfide types of ordinary cytochrome c due to reaction of the sulfhydryl group also occurred in the chymotrypsin-digested material. On the whole chymotrypsin-digested types of cytochrome c were rather more sensitive to bacterial proteinase than ordinary types. How-ever, the sulfhydryl type was less sensitive to proteinase than the disulfide type. This agrees with the results obtained on digestion of ordinary cytochrome c. It is concluded that
on partial hydrolysis with chymotrypsin and formation of the new compound, the confor-mation of cytochrome c did not undergo any fundamental alteration.
The author wishes to thank Dr. K. Nakanishi, a group manager in this laboratory, for his helpful advice. Thanks are also due to Dr. Y. Baba for amino acid analysis and to Mr. T. Akaike for his assistance in preparation of materials.