Cafaro V, Bracale A, Di Maro A, Sorrentino S, D'Alessio G, Di Donato A
Department of Organic and Biological Chemistry, University of Naples Federico II, Italy.
FEBS Lett. 1998 Oct 16;437(1-2):149-52. doi: 10.1016/s0014-5793(98)01221-6.
Monomeric bovine pancreatic RNase A has been transformed into a dimeric ribonuclease with antitumor activity (Di Donato, A., Cafaro, V. and D'Alessio, G. (1994) J. Biol. Chem. 269, 17394-17396). This was accomplished by replacing the residues located in the RNase chain at positions 19, 28, 31, and 32, with proline, leucine, and two cysteine residues, respectively, i.e. those present at identical positions in the subunit of bovine seminal RNase, a dimeric RNase of the pancreatic-type superfamily, endowed with a powerful antitumor action. However, as an antitumor agent this mutant dimeric RNase A is not as powerful as seminal RNase. We report here site-directed mutagenesis experiments which have led to the identification of two other amino acid residues, glycine 38 and 111, whose substitution in the polypeptide chain of the first generation dimeric mutant of RNase A, is capable of conferring to the mutein the full cytotoxic activity characteristic of native seminal RNase.
单体牛胰核糖核酸酶A已被转化为具有抗肿瘤活性的二聚体核糖核酸酶（迪多纳托，A.，卡法罗，V.和达莱西奥，G.（1994年）《生物化学杂志》269，17394 - 17396）。这是通过分别用脯氨酸、亮氨酸和两个半胱氨酸残基取代核糖核酸酶链中第19、28、31和32位的残基来实现的，即牛精浆核糖核酸酶亚基中相同位置存在的那些残基，牛精浆核糖核酸酶是胰腺型超家族的一种二聚体核糖核酸酶，具有强大的抗肿瘤作用。然而，作为一种抗肿瘤剂，这种突变的二聚体核糖核酸酶A不如精浆核糖核酸酶强大。我们在此报告定点诱变实验，这些实验已导致鉴定出另外两个氨基酸残基，即甘氨酸38和111，在核糖核酸酶A第一代二聚体突变体的多肽链中取代它们，能够赋予突变蛋白天然精浆核糖核酸酶特有的完全细胞毒性活性。
