The Structure and Function of Ribonuclease T1
III. Amino- and Carboxyl-Terminal Sequences of Ribonuclease T1
1962 年 52 巻 2 号 p. 72-81
詳細
1962 年 52 巻 2 号 p. 72-81
1. The N-terminal amino acid of RNase T1 was quantitatively determined to be alanine both by the DNFB-method and by the PTH-method.
2. The C-terminal amino acid of the enzyme was quantitatively determined to be threonine both by the hydrazinolysis method and by the carboxypeptidase method.
The above results indicated that RNase T1 is composed of a single open polypeptide chain.
3. The N-terminal sequence was investigated both by the stepwise degradation method of E d m a n and by the partial hydrolysis method and the six amino acid sequence from the terminus was deduced as follows; Ala•1/2Cys•Asp (or Asp-NH2)•Tyr•Thr•Asp(or Asp-NH2). The native enzyme as well as the oxidized enzyme was found to be rather resistant to the action of leucine aminopeptidase.
4. The C-terminal sequence was investigated by the carboxypeptidase method and the following sequence was elucidated: (Ser, Asp, Ala)•Val•Thr. The first two residues were found to be not essential for the enzymatic function of RNase T1, while the following portion was shown to be connected in some manner with the enzymatic function.
The author wishes to express his sincere thanks to Prof. F. Egami for his guidance and encouragement during this work. He also expresses his gratitude to Sankyo Co. Ltd. for the kind gift of “Takadiastase Sankyo”. The expense of this study was defrayed in part by a grant from the Ministry of Education.
