AMINO ACID COMPOSITIONS OF HUMAN AND RABBIT γ-GLOBULINS AND OF THE FRAGMENTS PRODUCED BY REDUCTION

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Abstract
Amino acid compositions have been determined, by using the Spinco model 120 Amino Acid Analyzer, for human and rabbit gamma-globulins, for the chains A and B separated after partial reduction of human and rabbit gamma-globulins, and for the A and B pieces obtained from piece II formed by papain digestion of rabbit gamma-globulin. The compositions of the rabbit-gamma-globulin chain B and B piece were not significantly different. Tryptophan was determined spectrophotometrically on the intact protein and cystine was determined as cysteic acid after oxidation of the protein. Oxidation of S-carboxymethylcysteine gave three products; one of these was eluted from the 150 cm. column of the Analyzer very close to the position of cysteic acid and was unstable to hydrolysis with acid. In contrast with a previous report, hydroxylysine could not be detected in either human gamma-globulin or rabbit gamma-globulin.