TY - JOUR
T1 - Thiol-quinone adduct formation in myofibrillar proteins detected by LC-MS
AU - Jongberg, Sisse
AU - Gislason, Nick E.
AU - Lametsch, Marianne Lund
AU - Skibsted, Leif Horsfelt
AU - Waterhouse, Andrew L.
PY - 2011/7/13
Y1 - 2011/7/13
N2 - Protein oxidation in meat is considered to decrease meat tenderness due to protein disulfide cross-link formation of thiol-containing amino acid residues. An LC-MS method for detection of thiol-quinone adducts (RS-QH2) in myofibrillar proteins was developed to investigate the interaction between phenols, as protective antioxidants, and proteins from meat under oxidative conditions using aqueous solutions of (i) cysteine (Cys), (ii) glutathione (GSH), (iii) bovine serum albumin (BSA), or (iv) a myofibrillar protein isolate (MPI). The aqueous solutions were incubated at room temperature (30 min) with 4-methyl-1,2-benzoquinone (4MBQ) prepared from oxidation of 4-methylcatechol (4MC) by periodate resin or incubated at room temperature (5 h) with 4MC and Fe(II)/H2O2. GSH, BSA, and MPI were hydrolyzed (6 N HCl, 110 °C, 22 h) after incubation, and the cysteine-quinone adduct, Cys-QH 2 (m/z 244.2) was identified according to UV and mass spectra after separation on an RP-C18 column. The thiol-quinone adduct was present in all thiol systems after incubation with 4MBQ or 4MC oxidized by Fe(II)/H 2O2. Direct reaction with 4MBQ resulted in each case in increased Cys-QH2 formation compared to simultaneous oxidation of thiol source and 4MC with Fe(II)/H2O2. The covalent bonds between quinones and thiol groups may act as a potential antioxidant by inhibiting disulfide protein cross-link formation.
AB - Protein oxidation in meat is considered to decrease meat tenderness due to protein disulfide cross-link formation of thiol-containing amino acid residues. An LC-MS method for detection of thiol-quinone adducts (RS-QH2) in myofibrillar proteins was developed to investigate the interaction between phenols, as protective antioxidants, and proteins from meat under oxidative conditions using aqueous solutions of (i) cysteine (Cys), (ii) glutathione (GSH), (iii) bovine serum albumin (BSA), or (iv) a myofibrillar protein isolate (MPI). The aqueous solutions were incubated at room temperature (30 min) with 4-methyl-1,2-benzoquinone (4MBQ) prepared from oxidation of 4-methylcatechol (4MC) by periodate resin or incubated at room temperature (5 h) with 4MC and Fe(II)/H2O2. GSH, BSA, and MPI were hydrolyzed (6 N HCl, 110 °C, 22 h) after incubation, and the cysteine-quinone adduct, Cys-QH 2 (m/z 244.2) was identified according to UV and mass spectra after separation on an RP-C18 column. The thiol-quinone adduct was present in all thiol systems after incubation with 4MBQ or 4MC oxidized by Fe(II)/H 2O2. Direct reaction with 4MBQ resulted in each case in increased Cys-QH2 formation compared to simultaneous oxidation of thiol source and 4MC with Fe(II)/H2O2. The covalent bonds between quinones and thiol groups may act as a potential antioxidant by inhibiting disulfide protein cross-link formation.
U2 - 10.1021/jf200965s
DO - 10.1021/jf200965s
M3 - Journal article
C2 - 21599024
SN - 0021-8561
VL - 59
SP - 6900
EP - 6905
JO - Journal of Agricultural and Food Chemistry
JF - Journal of Agricultural and Food Chemistry
IS - 13
ER -