Spectrofluorimetric determination of cysteine by 5-maleimidyl-2-(m-methylphenyl)benzoxazole.
A new thiol weak-fluorescence probe, 5-maleimidyl-2-(m-methylphenyl)benzoxazole (MMPB), gives a highly fluorescence product in the presence of Cys. In this paper, MMPB has been developed for the fluorimetric determination of cysteine (Cys). At lambda(ex)/lambda(em) = 305.6/425.6 nm, the linear range is from 0 to 3.3 x 10(-7) mol l(-1) and the detection limit (sigma = 3) of 6.2 x 10(-10) mol l(-1). The main advantage of this method lies in the relative high selectivity compared with the methods using other N-substituted maleimide type of thiol reagents, in which 0.15-fold (molar ratio) of GSH is allowed and most of other amino acids at 100-fold (molar ratio) level had no obvious effect on the results. The proposed method has been applied to the determination of Cys in real samples.
Liang
Shu-Cai
SC
Department of Chemistry, Wuhan University, People's Republic of China. hshzhang@whu.edu.cn
Wang
Hong
H
Zhang
Zhi-Min
ZM
Zhang
Xian
X
Zhang
Hua-Shan
HS
D001583:Benzoxazoles / Q000737:chemistry*; D003545:Cysteine / Q000032:analysis* / Q000652:urine; D005456:Fluorescent Dyes / Q000737:chemistry*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents; D008301:Maleimides / Q000737:chemistry*; D011506:Proteins / Q000032:analysis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence / Q000379:methods* / Q000592:standards; D013696:Temperature
C474746:5-maleimidyl-2-(m-methylphenyl)benzoxazol; D001583:Benzoxazoles; D005456:Fluorescent Dyes; D007202:Indicators and Reagents; D008301:Maleimides; D011506:Proteins; D003545:Cysteine