Specificity of Kerateine Derivatives

Abstract

In a previous communication, 1 it was shown that species specificity is an individual characteristic of the keratins. The suggestion was offered that the redox state and spatial arrangement of the amino acids cystine and cysteine may be intimately connected with the specificity of these proteins.

In this article it will be shown that the substitution of the hydrogen in the -SH groups of reduced keratin (kerateine) with organic halogen compounds gives the protein a new immunological character dependent on the introduced “determinant group.”

Since keratins contain a very high percentage of di-sulfide sulfur (10 to 15% cystine) and are readily reduced to sulphydryl proteins by alkaline thioglycolate, a large number of substituent groups may be introduced into their molecules by reaction with simple organic halogen compounds according to the following formula:

Such a reaction occurs readily in a mildly alkaline environment, 2 and this has been applied to proteins by Mirsky and Anson, 3 and Goddard and Schubert. 4 The method involves a mild treatment of the protein and has the added advantage of being carried out at a pH of 8.

Although Michaelis and Schubert 5 have observed that organic halogens react with amino groups, there was no demonstrable substitution of the amino groups under the conditions employed in these experiments, while complete or near complete substitution of the sulphydryl groups was accomplished.

The derivatives studied were prepared from wool and feather kerateine by reaction with iodo-acetic acid, alpha bromo-propionic acid, alpha bromo-n-butyric acid, alpha bromo-iso-butyric acid, alpha bromo-n-valeric acid, alpha bromo-iso-valeric acid, alpha bromo-n-caproic acid, alpha bromo-ethyl-benzene. and benzyl chloride.