Pyruvate kinaseのNucleotide特異性について

Nuclotide Specificity of Pyruvatekinase

　筋肉及び酵母より精製したpyruvate kinaseのnucleotide特異性について研究して次の結果をえた。

（1）何れの酵素もリン酸受容体としてADP，GDP，IDP，UDP，CDPが有効である。その相互活性比は本実験の条件下では筋肉の酵素ではA：G：U：I：C＝100：67：18：17：10，酵母の酵素ではA：U：C：G：1＝100：10：6：5：3であつた。

（2）各nucleotideの至適pHを求めた結果，筋肉の酵素では何れも7.2-7.5の間にあって著しい差が認められなかつたが酵母の酵素では5.8から70の間にあつて，かなりの差異を認めた。

　稿を終るに臨み，終始御懇切なる御指導御校閲を賜つた島薗順雄教授に厚く感謝する。又研究に際し種々御助言を頂いた真野嘉長講師に感謝する。

　Nucleotide specificity of purified pyruvate kinases from muscle and baker's yeast was studied and the following results were obtained: (1) ADP, GDP, IDP, UDP, and CDP were effective as phosphate acceptor in both enzymes. Under the conditions tested the reaction velocities were in the ratio of ADP: GDP: UDP: IDP: CDP=100: 67: 18: 17: 10 in the muscle enzyme at pH 7.4, and ADP: UDP: CDP: IDP=100: 10: 6: 5: 3 in the yeast enzyme at pH 5.8.

　(2) Under the condition tested, the pH optima of the nucleotides were not so different from each other in the muscle enzyme, namely, they were 7.43, 7.37, 7.21, 7.38, and 7.50 in the cases of ADP, GDP, IDP, UDP, and CDP, respectively, whereas in the yeast enzyme they were rather different from each other, namely, 5.8, 5.8, 7.0, 6.0, and 7.0 in the cases of ADP, GDP, IDP, UDP, and CDP, respectively.