Kimura M, Sumizawa T, Funatsu G
Laboratory of Protein Chemistry and Engineering, Faculty of Agriculture, Kyushu University, Fukuoka, Japan.
Biosci Biotechnol Biochem. 1993 Jan;57(1):166-9. doi: 10.1271/bbb.57.166.
The amino acids of the B-chains of two abrins (designated as abrin-a and abrin-b) from the seeds of Abrus precatorius have been sequenced. The sequence of the B-chain of abrin-a was solved by analysis of peptides derived by enzymatic digestions with trypsin, lysylendopeptidase, and chymotrypsin, as well as by chemical cleavage with cyanogen bromide. The sequence of the B-chain of abrin-b was analyzed by sequence analysis of tryptic peptides and comparing these sequences with those of corresponding peptides of the B-chain of abrin-a. The B-chains of abrin-a and abrin-b consist of 268 amino acid residues and share 256 identical residues. Comparison of their sequences with that of the ricin B-chain shows that 60% of the residues of both abrin B-chains are identical to those of the ricin B-chain and that two saccharide-binding sites in ricin B-chain identified by a crystallographic study are highly conserved in both abrin B-chains.
已对来自相思子种子的两种相思子毒素（分别命名为相思子毒素-a和相思子毒素-b）的B链氨基酸进行了测序。相思子毒素-a的B链序列是通过对用胰蛋白酶、赖氨酰内肽酶和胰凝乳蛋白酶进行酶促消化以及用溴化氰进行化学裂解所得到的肽段进行分析而确定的。相思子毒素-b的B链序列是通过对胰蛋白酶肽段进行序列分析并将这些序列与相思子毒素-a的B链相应肽段的序列进行比较来分析的。相思子毒素-a和相思子毒素-b的B链均由268个氨基酸残基组成，共有256个相同的残基。将它们的序列与蓖麻毒素B链的序列进行比较表明，两种相思子毒素B链60%的残基与蓖麻毒素B链的残基相同，并且通过晶体学研究确定的蓖麻毒素B链中的两个糖结合位点在两种相思子毒素B链中都高度保守。
