Abstract

Six groups of ribonucleases (RNases) activities from Sweet potato (Ipomoea batatas Lam. Cv. Tainong 57) leaves were identified and characterized by an RNA-cast polyacrylamide gel. Among these ribonucleases, five were major isoforms, and were designated to A-E groups, ranged in size from 14 to 47 kilodalton. They were consistently expressed in root, stem and leaf. In addition, a novel RNase isoform, designated F group, with a molecular mass about 6000 dalton, expressed specifically in the aging leaf. In this paper the biochemical properties of six groups RNase isoforms were characterized with catalytic ions, pH value, denaturing reagent of SDS and 2-mercaptoethanol.

中文摘要

我們利用核醣核酸電泳膠片技術已經成功地分析出甘薯〈台農57號〉核醣核酸水解酵素的一些蛋白質特性及基本性質。在甘薯的根、莖、葉中有介於 14-47 kDa分子量的五群核醣核酸水解酵素 (A-E) 恆定表現。然而卻有一低分子量〈約9,000 kDa〉核醣核酸水解酵素在甘薯老化的葉片裡大量合成並且表現出來，我們稱此特殊表現的蛋白質為 F 群核醣核酸水解酵素。在此篇文章中，我們探討這六群核醣核酸水解酵素之生化活性與 pH 值、離子種類和濃度的關聯性，並利用 SDS 和 2-mercaptoethanol 變性劑觀察此類酵素的生化活性。

Keyword: Sweet potato, RNase, Ipomoea batatas, s-RNase. 甘薯，核醣核酸水解酵素，自我不親和性核醣核酸水解酵素。