A method for the independent determination of cysteine and cystine in proteins

R D STRICKLAND, E L MARTIN, J L RIEBSOMER
1954 Journal of Biological Chemistry  
There are a number of analytical procedures for the determination of cysteine in the presence of cystine, but all of them depend upon having the two substances as free compounds. It has not been possible to determine the separate amounts of cysteine and cystine groups in protein molecules because no means have been available for preventing interconversion of the two compounds during hydrolysis. A method for the separate determination of cystine and cysteine as they exist in proteins should be
more » ... roteins should be of value in the study of physiological oxidationreduction processes involving the reversible conversion of two sulfhydryl groups to a disulfide link. Such a method should also make possible the investigation of the effect of sulfur linkages on the properties of the keratins and other proteins. This paper describes a method which was developed to meet the need for independent determinations of these two amino acids in proteins. Method
pmid:13163075 fatcat:2i2mq6ief5gbhjror62ka5e2zq