具有合成核酸活性的多肽 Ⅰ.C-端去四肽和去六肽核糖核酸酶A及其水解和合成活性

Study on Nucleic Acid-Synthesizing Polypeptides Ⅰ. C-Terminal Destetrapeptid-and Deshexapeptido-Ribonuclea■ and their Hydrolytic and Synthetic Activities

核糖核酸酶A(RNase A)的结构与功能的关系虽属已知[1-9],但大都限于水解作用方面,而关于合成作用方面的报道则颇少[10,11].根据前人用抑制剂法所得羧甲基化核糖核酸酶A的衍生物(CM-RNase A).

C-Terminal destetrapaptido-and deshexapeptido-ribonucleases A(RA■RA1-118)were prepared from ribonuclease A(RNase A)by peptic digestion■RA1-120 by limited carboxypeptidase A action respectively.Both RA■RA1-118 have definite though significantly weaker hydrolytic activities,esp■weak ribonucleoside 2’,3’-cyclo-phosphate-hydrolysis activities,but not■synthetic activities than those of natural RNase A.At room temperature,■initial velocities of the hydrolysis of U>p by RNase A,RA1-120 and RA■found to be 100,2 and 0.7 respectively.The relative synthetic activities of■A.RA1-120 and RA1-118 at-15℃were determined to be 100,120 and 167,i■U>p and Cwere used as substrates and the yields of UpC enzymatically■in 24h at-15℃were compared.From the above results it is concluded that Hisof RNase A molecule is■but not necessary for its hydrolytic activity and neither important nor necessa■synthetic activity.