Mohd Asraf Mohd Zainudin
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Preferred name
Mohd Asraf Mohd Zainudin
Official Name
Mohd Asraf, Mohd Zainudin
Alternative Name
Mohd Zainudin, Mohd Asraf
Zainudin, M. A.M.
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Scopus Author ID
55539687700
Researcher ID
AAV-4476-2020

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  • Publication
    Quantitation of Protein Cysteine-Phenol Adducts in Minced Beef Containing 4-Methyl Catechol
    ( 2020-02-26)
    Arsad S.S.
    ;
    Mohd Asraf Mohd Zainudin
    ;
    De Gobba C.
    ;
    Jongberg S.
    ;
    Larsen F.H.
    ;
    Lametsch R.
    ;
    Andersen M.L.
    ;
    Lund M.N.
    Thiol groups of cysteine (Cys) residues in proteins react with quinones, oxidation products of polyphenols, to form protein-polyphenol adducts. The aim of the present work was to quantify the amount of adduct formed between Cys residues and 4-methylcatechol (4MC) in minced beef. A Cys-4MC adduct standard was electrochemically synthesized and characterized by liquid chromatography-mass spectrometry (LC-MS) as well as NMR spectroscopy. Cys-4MC adducts were quantified after acidic hydrolysis of myofibrillar protein isolates (MPIs) and LC-MS/MS analysis of meat containing either 500 or 1500 ppm 4MC and stored at 4 °C for 7 days under a nitrogen or oxygen atmosphere. The concentrations of Cys-4MC were found to be 2.2 ± 0.3 nmol/mg MPI and 8.1 ± 0.9 nmol/mg MPI in meat containing 500 and 1500 ppm 4MC, respectively, and stored for 7 days under oxygen. The formation of the Cys-4MC adduct resulted in protein thiol loss, and ca. 62% of the thiol loss was estimated to account for the formation of the Cys-4MC adduct for meat containing 1500 ppm 4MC. Furthermore, protein polymerization increased in samples containing 4MC as evaluated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and the polymerization was found to originate from protein-polyphenol interactions as evaluated by a blotting assay with staining by nitroblue tetrazolium.
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