我国大豆种子球蛋白2S组分的研究——2S球蛋白的某些性质

STUDY ON 2S FRACTON OF SOYBEAN. SEED GLOBULIN: PROPERTIKS OF 2S GLOBULIN

本实验对2S球蛋白的四个组分进行了SDS—PAGE分子量测定,氨基酸组成分析,沉降超离心分析,Dansy1—C1法N—末端氨基酸测定和蛋白酶抑制剂活性测定。结果表明:2S球蛋白四个组分的分子量按SⅡP_1,SⅡP_2,SⅡP_3和SⅡP_4的顺序分别为22,800,21,500,19,200和17,800。所含残基数分别为191,179,163和147个。SⅡP_1,SⅡP_2和SⅡP_3三者的沉降系数(Sw.20)分别为2.1S,1.9S和1.8S。N—末端分析表明这四种蛋白质的N—末端均为天冬氨酸。还发现只有SⅡP_2具有丝氨酸类蛋白酶抑制剂活性。本实验所提纯的这个抑制剂(SⅡP_2)的一个ATEE单位为0.4ug抑制剂蛋白(特指对α—chymotrypsin发生作用时)。α—chymotrypsin与此抑制剂(SⅡP_2)相互作用时的克分子数比为E/I=2/1。

In this experiment the four fractions of 2s globulin were characterized in following aspects: the determination of molecular weights ,with method of -SDS-PAGE; the analysis of amino acid composition; the determination of sedimentation constant:the determination of N-terminal amino acid by Dansyl-CL thinlayer chromatography and the detection of their protease inhibition activities.The results from above experiments showed that the M. W. S of the four components are 22 800 ,21 5000 , 19 200, and 17 800 respectively. The residue numbers of the four compenets are . SⅡP1=191, SⅡP2 = 179, SⅡP3 = 163and SⅡP4=147. The sedimentation constants of S Ⅱ P2, and S Ⅱ P3 are proved to be 2.1s, 1.9s and 1.8s. The terminal'analysis tells that each of the four proteins has Asp as its N-terminal amino acid. It was also found that only SⅡ P2 has the activity of inhibiting serins proteinases. The molecalar number ratio of E/I ( only refers to-chymotrypsin/S Ⅱ P2 ) is 2/1.