Riboflavin photosensitized oxidation of myoglobin

Research output: Contribution to journalJournal articleResearchpeer-review

Juliana M. Grippa, Andressa Zawadzki, Alberto Blak Grossi, Leif Horsfelt Skibsted, Daniel R. Cardoso

The reaction of the fresh meat pigment oxymyoglobin, MbFe(II)O, and its oxidized form metmyoglobin, MbFe(III), with triplet-state riboflavin involves the pigment protein, which is oxidatively cleaved or dimerized as shown by SDS-PAGE and Western blotting. The overall rate constant for oxidation of MbFe(II)O by Rib is (3.0 ± 0.5) × 10 L·mol·s and (3.1 ± 0.4) × 10 L·mol·s for MbFe(III) in phosphate buffer of pH 7.4 at 25 C as determined by laser flash photolysis. The high rates are rationalized by ground state hydrophobic interactions as detected as static quenching of fluorescence from singlet-excited state riboflavin by myoglobins using time-resolved fluorescence spectroscopy and a Stern-Volmer approach. Binding of riboflavin to MbFe(III) has K = (1.2 ± 0.2) × 10 mol·L with ΔH = -112 ± 22 kJ·mol and ΔS = -296 ± 75 J·mol·K. For meat, riboflavin is concluded to be a photosensitizer for protein oxidation but not for discoloration.
Original languageEnglish
JournalJournal of Agricultural and Food Chemistry
Volume62
Issue number5
Pages (from-to)1153-1158
Number of pages6
ISSN0021-8561
DOIs
Publication statusPublished - 2014

ID: 101952355