Structural Studies on the Coat Protein of Alfalfa‐Mosaic Virus

Abstract

The investigation described in this paper deals with various aspects of the primary structure of the coat protein of the plant virus alfalfa‐mosaic virus (AMV 425). The N‐terminus of this protein has been identified as N ‐acetylserine, the C‐terminal structure is ‐Arg‐His · COOH. Cyanogen bromide cleavage of the reduced and carboxymethylated protein yields four major peptide fragments which is in accordance with the presence of three methionine residues in the intact protein chain. These fragments have been separated and characterized by amino acid analysis, electrophoretic behaviour on polyacrylamide gel, end‐group determination and molecular weight. Together they account for all the amino acid residues in the entire protein chain. The alignment of the peptide fragments along the chain is presented. The data lend strong support to the molecular size of this protein reported previously from this laboratory.