FORMATION OF BASIC AMINO ACIDS ON TREATMENT OF PROTEINS WITH ALKALI

1. 1. Four proteins of known sequence (lysozyme, myoglobin, ribonuclease and insulin) have been treated with NaOH and ammonia solutions, and the amounts of lysinoalanine and β-aminoalanine estimated in the hydrolysates by high-voltage paper electrophoresis. The relative amounts of each amino acid are explained by reference to the positions of cystine and serine residues in relation to lysine residues and amide side-chains in the proteins. 2. 2. The evidence indicates that β-aminoalanine is formed by direct addition of ammonia to α-aminoacrylic acid residues, and not by initial formation of a cross-link between α-aminoacrylic acid and asparagine or glutamine residues. 3. 3. Further evidence has been found for the formation of α-aminoacrylic acid from residues other than cystine, by treatment of myoglobin with alkali. 4. 4. Treatment of β-lactoglobulin and wheat gluten, whose sequences are unknown, has enabled tentative suggestions to be made about the relative positions of certain residues in these proteins. © 1969.