Purification and Characterization of the Constituent Polypeptide Chains of Abrus precatorius Agglutinin

抄録

Abrus precatorius agglutinin (APA) bound to an acid-treated Sepharose 4B column was reduced with 2-mercaptoethanol and the A-chain released from APA was eluted. After repeating this procedure three times, the remained B-chain was eluted from the column with lactose. Both the chains were put through fast protein liquid chromatography using a Mono Q column and pure A-, B₁-, and B₂-chains were isolated.
The A-, B₁-, and B₂-chains were acidic glycoproteins having molecular weights of 30, 000, 32, 000, and 33, 000, and isoelectric points of 3.8, 5.4, and 5.6, respectively. The B₁ and B₂-chains have identical N-terminal sequences and similar amino acid compositions, and contain 6.80 and 9.12% sugar, respectively. These results indicated that the difference in their molecular weight might be due to the variation in sugar contents. Furthermore, the very low cytoagglutinating activity of the isolated B-chains suggested their monovalent nature.