Nitta K, Oyama F, Oyama R, Sekiguchi K, Kawauchi H, Takayanagi Y, Hakomori S, Titani K
Department of Biochemistry, Tohoku College of Pharmaceutical Sciences, Sendai, Japan.
Glycobiology. 1993 Feb;3(1):37-45. doi: 10.1093/glycob/3.1.37.
Sialic acid-binding lectin (SBL) isolated from Rana catesbeiana eggs is a basic protein which agglutinates a large variety of tumour cells and has an amino acid sequence homologous to that of human angiogenin and pancreatic ribonuclease (RNase). Although SBL and angiogenin lack the Cys-65-Cys-72 disulphide bond of pancreatic RNase, the locations of the other three disulphide bonds are similar among the three molecules. SBL was found to exhibit RNase activity, as well as catalytic properties resembling those of bovine RNase A in some respects. For example, SBL hydrolyses poly(uridylic acid) and poly(cytidylic acid) as substrates, and prefers the former. RNase A and angiogenin are strongly inhibited by human placental RNase inhibitor, whereas the RNase activity and tumour cell agglutination activity of SBL are not affected by this inhibitor.
从牛蛙卵中分离出的唾液酸结合凝集素（SBL）是一种碱性蛋白质，它能凝集多种肿瘤细胞，其氨基酸序列与人类血管生成素和胰腺核糖核酸酶（RNase）的氨基酸序列同源。尽管SBL和血管生成素缺乏胰腺RNase的Cys-65-Cys-72二硫键，但这三种分子中其他三个二硫键的位置相似。研究发现SBL具有RNase活性，并且在某些方面具有类似于牛RNase A的催化特性。例如，SBL以聚（尿苷酸）和聚（胞苷酸）为底物进行水解，并且更倾向于前者。RNase A和血管生成素受到人胎盘RNase抑制剂的强烈抑制，而SBL的RNase活性和肿瘤细胞凝集活性不受该抑制剂的影响。
