【摘要】 <正> 核糖核酸酶A（RNase A）的结构与功能的关系虽属已知,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.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）,和用合成法所得分子较简单的RNase A的类似物的研究结果,似乎RNaseA分子中的His₁₁₉与Lys₄₁残基与酶的合成活性无关.这些衍生物和类似物的合成活性都比它们的水解活性高,但不论它们的合成或水解活性都很显著地低于天然酶的活更多还原

【Abstract】 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 C_R were used as substrates and the yields of UpC enzymatically（?） in 24h at -15℃ were compared.From the above results it is concluded that His₁₁₉ of RNase A molecule is（?） but not necessary for its hydrolytic activity and neither important nor necessa（?） synthetic activity.更多还原