[35] Detection of peptides by chemical methods

TLDR: This chapter describes various chemical methods used in the detection of peptides and the reaction of ninhydrin with peptides, which is a complex reaction at α- and ɛ-amino groups and hydrolysis.

Abstract: Publisher Summary This chapter describes various chemical methods used in the detection of peptides The reactions with ninhydrin and with the Folin-Lowry reagent are both used for the detection and estimation of peptides in solution The reaction of ninhydrin with peptides is complex because, in addition to reaction at α- and ɛ-amino groups, hydrolysis may also occur The rates of these processes are a function of the structure of the peptide The variability of color yield is decreased and the overall sensitivity of the procedure is increased when the peptide is first subjected to hydrolysis Three major chemical methods discussed are (1) ninhydrin reagent, (2) alkaline hydrolysis, and (3) ninhydrin reaction Ninhydrin reagent involves three preparation steps, namely––the methyl cellosolve, buffer solution 4M, pH 5 , and preparation and storage of reagent In alkaline hydrolysis, the reaction is performed in polypropylene test tubes and the samples to be analyzed are carefully pipetted into the bottoms of the tubes The procedure of the ninhydrin reaction is also discussed