Protocols for the analysis of the sulfhydryl content in peptides and proteins using chemical derivatization by organomercurial reagents and analysis by matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) have been developed. The number of reactive cysteine residues in peptides a
Determination of cysteine plus half-cystine in protein and peptide hydrolysates: Use of dithiodiglycolic acid and phenylisothiocyanate derivatization
β Scribed by John G. Hoogerheide; Carla M. Campbell
- Publisher
- Elsevier Science
- Year
- 1992
- Tongue
- English
- Weight
- 667 KB
- Volume
- 201
- Category
- Article
- ISSN
- 0003-2697
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β¦ Synopsis
Cysteine and half-cystine in proteins and peptides can be determined by acid hydrolysis in the presence of dithiodiglycolic acid, derivatization with phenyl isothiocyanate, and HPLC separation of the phenylthiocarbamyl amino acids. The determination requires no additional sample handling, oxidation, reduction, alkylation, or desalting. Samples containing cystine are treated in the same manner as those containing cysteine. Derivatization of cysteine or half-cystine by dithiodiglycolic acid has no effect on any other amino acids. Recovery of the PTC-cysteine derivative is greater than 90% over the linear range of 5 pmol to 1 nmol. Precision of the cysteine plus half-cystine determination is equivalent to that observed for all other amino acids. Structure work on the derivative indicates that it is a mixed disulfide containing cysteine and thioglycolic acid.
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Biologically Important sulphydryl compounds, e g cysteme, were determined by treatmg the reductant tluol with copper(B)-neocuprom (NC) reagent m ammonium acetate-buffered medium, followed by measunng the absorbance of the copper(I)-Nc complex at 450 nm Cystme, d present m a rmxture Hnth cysteme, was
Hydrolysis of proteins and peptides with mercaptoethane sulfonic acid is liable to produce overestimation of the proline content owing to the production of ninhydrin-positive material (probably cysteine) which coelutes with proline on many ion-exchange analytical systems. A similar error occurs with