ABSTRACT
The specific chemical modification of tryptophan in protein is one of the more challenging problems in protein chemistry. First, as will be apparent, the solvent conditions for providing specificity of modification are, in general, somewhat harsh. Secondly, there is the considerable possibility of either the concomitant or separate modification of a different amino acid residue. Thirdly, the analysis for the determination of the exact extent of modification requires a rigorous approach combining spectral analysis and amino acid analysis after hydrolysis in a solvent which will not destroy tryptophan. Treatment of tryptophan with hydrogen peroxide results in the oxidation of the indole ring. The use of oxidation with N-bromosuccinimide to determine the tryptophan content of proteins can be of some value. The study on the modification of tryptophan in galactose oxidase is worth comment in that the investigators report the amino acid composition of the modified protein after hydrolysis in 3 N/j-toluenesulfonic acid.
