Cysteine Racemization in Peptide Synthesis: A New and Easy Detection Method

✍ Scribed by Frank Siedler; Elisabeth Weyher; Luis Moroder

• Book ID: 105360653
• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 368 KB
• Volume: 2
• Category: Article
• ISSN: 1075-2617
• DOI: 10.1002/psc.83

✦ Synopsis

A new method has been developed for the rapid determination of D-cysteine contents in synthetic peptides. It is based on the reduction of cystine residues, when present, with tris-alkylphosphines, selective derivatization of the cysteine residues with 4-vinylpyridine, followed by acid hydrolysis of the (4-pyridylethyl)cysteine-peptides. Baseline enantiomeric resolution of the D,L-S-beta-(4-pyridylethyl)cysteine, and thus quantification of D-enantiomer contents at levels < or = 1%, is easily achieved by capillary zone electrophoresis exploiting the host-guest complexation principle with crown ethers or by gas chromatography on chiral glass capillary columns upon conventional derivatization of the hydrolysate. The acid-stability of the (4-pyridylethyl)cysteine derivative prevents racemization via thiazoline intermediates and allows for standardization of the acid hydrolysis-dependent racemization.