Synthesis of Silver Proteinates for Neurological Staining

Abstract

Soluble derivatives of the AgNO3 precipitates of various split protein products were prepared by dissolving the precipitate in a 30-40% aqueous solution of pharmaceutical peptone (Cudahy). The split proteins used included pepsin, trypsin and papain digests of albumin, globulin, gelatin, casein, protamine, and tissue proteins from heart, liver and brain; also, an Escherichia coli digest of casein, and commercial products: Amigen (Mead), casein hydrolysate (Squibb) and pharmaceutical peptone (Cudahy). Staining reactions of the silver derivatives were tested on mammalian nervous tissue. The objective of finding a silver-protein compound that stained axis cylinders selectively was attained only with redissolved silver precipitates of pharmaceutical peptone and bacterially digested casein. It was concluded that the manner of degrading a protein prior to combining it with silver was the most important factor in determining the subsequent staining reaction.