摘要
采用多种凝胶电泳技术对用过滤层析法分离的拟南芥菜(Arabidopsis thaliana)的主要种子蛋白(组分Ⅰ和Ⅱ)进行了研究。结果表明,组分Ⅰ在 SDS 电泳中被分离成分子量分别为34、31、29、28和19—20kD 的6条带,组分Ⅱ分离形成3条低分子量的带(10—12kD)。未变性蛋白质凝胶电泳分析揭示了组分Ⅰ为一呈中性的蛋白质,而组分Ⅱ则是一带正电荷的碱性蛋白质,其等电点高于8.8。在 IEF/SDS 双维电泳中,组分Ⅰ至少被分离成16个多肽分子,即每一条 SDS 带包含有3—4个具相同分子量,不同等电点的多肽分子。组分Ⅰ和Ⅱ的这些性质与在其他双子叶植物种子中已被鉴定的12s 和1.7s 贮藏球蛋白的完全符合,因此被确定为拟南芥菜的两种主要种子贮藏蛋白。这两种球蛋白在种子发育后期的一个特定时期内(开花后10—14天)积累,并在成熟种子中占总蛋白的绝大部分。
This study was aimed at the characterization of the major storage proteins in Arabidop- sis thaliana.Two major protein fractions,i.e,the fractionⅠandⅡproteins,were isolated from the extract of mature seeds of this plant by molecular seive gel filtration chromatography. Various polyacrylamide gel electrophoretic techniques were used to study the properties and polypeptide compositions of these two protein fractions.In was shown that during the SDS gel electrophoresis,fractionⅠprotein was separated into 6 major bands with the mol.wts.of 34,31,29,28 and 19—20 kD,respectively,whereas FractionⅡprotein migrated as 3 low tool. wt.bands (10—12kD) on the same gel.Non-denaturing native gel electrophoresis revealed that fractionⅠwas a neutral protein and FractionⅡwas a positively-charged basic protein with an isoelectric point (pl) higher than 8.8.FractionⅠprotein was further separated into at least 16 polypeptides in isoelectric focusing/SDS two-dimensional gel electrophoresis,i.e. each SDS band contained 3—4 polypeptides with the same mol.wt.but different pls.This suggested a more complex polypeptide composition of this protein.The properties of frac- tionⅠandⅡ proteins were in good accordance with of the 12s and 1.7s storage globulins in seeds of many other dicotyledonous plants,and therefore had been characterized as the two major seed storage proteins in this species.These two storage globulins were shown to be accumulated within a defined period during the late stage of seed development (12—14 DAF) and became predominant protein components in mature seeds.In the mean time,a few points in relation to the polypeptide composition and subunit molecular configuration of the- 12s globulin were noted.
关键词
拟南芥菜
种子
贮藏蛋白
凝胶电泳
Seed storage protein
Gel electrophoresis
Two-dimensional gel electrophoresis
Arabidopsis thaliana
