title: Quantification of protein thiols using ThioGlo 1 fluorescent derivatives and HPLC separation.
abstract: A method for quantification of total soluble protein-derived thiols in beer was developed based on the formation of fluorescent adducts with the maleimide compound ThioGlo 1. The problem of interference from fluorescent adducts of sulfite and ThioGlo 1 was solved by HPLC separation of the adducts followed by fluorescence detection. Using standard addition of GSH, a detection limit of 0.028 μM thiols was achieved. The application and validation of the method was demonstrated for beers with different color intensities, and the application range is in principle for any biological system containing thiols. However, the quantification of cysteine was complicated by a lower fluorescence response of its ThioGlo 1 adducts. Based on the studies of the responses of a series of cysteine-derived thiols and (1)H NMR studies of the structures of ThioGlo 1 adducts with GSH and cysteine, it was concluded that thiols with a neighboring free amino group yield ThioGlo 1 adducts with a reduced fluorescence intensity.
authors: Department of Food Science, University of Copenhagen, Rolighedsvej 30, DK-1958 Frederiksberg C, Denmark. hoff@life.ku.dk
authors: Signe
authors: S
authors: Hoff
authors: Flemming H
authors: FH
authors: Larsen
authors: Mogens L
authors: ML
authors: Andersen
authors: Marianne N
authors: MN
authors: Lund
mesh_terms: D001515:Beer / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003545:Cysteine / Q000737:chemistry; D005456:Fluorescent Dyes / Q000737:chemistry; D005978:Glutathione / Q000737:chemistry; D009281:Naphthalenes; D019906:Nuclear Magnetic Resonance, Biomolecular; D011506:Proteins / Q000737:chemistry*; D011758:Pyrroles; D013438:Sulfhydryl Compounds / Q000032:analysis*
chemical_list: D005456:Fluorescent Dyes; D009281:Naphthalenes; D011506:Proteins; D011758:Pyrroles; D013438:Sulfhydryl Compounds; C498335:ThioGlo-1; D005978:Glutathione; D003545:Cysteine