【摘要】 核糖核酸酶A具有DNA结合蛋白的作用。本文报道,核糖核酸酶A经枯草杆菌蛋白酶作用后,被切断而形成一个20肽和s-蛋白。分离纯化后的s-蛋白完全丧失了水解RNA的酶活性,却完全保持着作为DNA结合蛋白的活性。这个结果说明核糖核酸酶A表现RNA水解酶活力与其同DNA的结合作用对结构的要求有所不同。对s-蛋白与双链及单链DNA结合作用的研究还表明,在这种结合过程中s-蛋白分子中的酪氨酸和苯丙氨酸残基的萤光发生淬灭作用,可能系因s-蛋白中的这些氨基酸残基直接参与了与DNA的结合,RNaseA经枯草杆菌蛋白酶作用切除s-肽后产生的s-蛋白的α-螺旋含量由RNaseA的17.5%增加到23.7%。更多还原

【Abstract】 S-protein was isolated from RNase A by polyacrylamide gel electrophoresis afterproteolytic digestion with subtilisin. Like RNase A, the S-protein shows the samebehavior of shifting the melting temperature of double stranded DNA although it doesnot show any ribonuclease activity. The fluorescence of tyrosine and phenylalanineresidues of S-protein were quenched by the addition of single stranded DNA. For the hydrolysis of RNA, the whole RNase A molecule is needed; whereas forbinding to DNA the S-protein is enough. The S-protein of RNase A does not showRNase activity, so it may be useful in studying the replication and transcription ofRNA. The content of α-helix of S-protein was increased after treatment of RNase Awith subtilisin.更多还原