title: The complete amino acid sequences of the B-chains of abrin-a and abrin-b, toxic proteins from the seeds of Abrus precatorius.
abstract: 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.
authors.affiliation: Laboratory of Protein Chemistry and Engineering, Faculty of Agriculture, Kyushu University, Fukuoka, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Kimura
authors.forename: T
authors.initials: T
authors.lastname: Sumizawa
authors.forename: G
authors.initials: G
authors.lastname: Funatsu
mesh_terms: D000036:Abrin / Q000737:chemistry*; D000595:Amino Acid Sequence; D002851:Chromatography, High Pressure Liquid; D002918:Chymotrypsin / Q000378:metabolism; D003488:Cyanogen Bromide / Q000737:chemistry; D008969:Molecular Sequence Data; D012697:Serine Endopeptidases / Q000378:metabolism; D014357:Trypsin / Q000378:metabolism
chemical_list: D000036:Abrin; D012697:Serine Endopeptidases; D002918:Chymotrypsin; D014357:Trypsin; C036813:lysyl endopeptidase; D003488:Cyanogen Bromide