Simultaneous spectrophotometric determination of cystine and cysteine in amino acid mixtures using copper(II)—neocuproin reagent

✍ Scribed by Esma Tütem; Reşat Apak

• Publisher: Elsevier Science
• Year: 1991
• Tongue: English
• Weight: 429 KB
• Volume: 255
• Category: Article
• ISSN: 0003-2670
• DOI: 10.1016/0003-2670(91)85096-b

✦ Synopsis

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 reduced to the latter with zmc-hydrochlonc acid poor to the colour reaction Many common ammo acids (not contammg the SH group) and reducmg sugars dtd not interfere, and colour development took 2 mm Ascorbic acid, glutathione and penmllamme gave slrmlar colour reations to cysteme For cysteme, the molar absorptmty was 7 5 x lo3 1 mol-' cm-' with a relative standard deviation of 3%, rendermg the method smtable for routme work with good prec~ion The method was successfully applied to the assay of cystme m soybean protein hydrolysate, and the results were compared to those obtained by hqmd chromatography Keywords Spectrophotometry, Ammo acids, Cysteme, Cystme Cysteme, HSCH,CH(NH,)COOH,