Riboflavin Photosensitized Oxidation of Myoglobin

Author(s)

Grippa, Juliana M. ^[1] ; de Zawadzki, Andressa ^[1] ; Grossi, Alberto B. ^[2] ; Skibsted, Leif H. ^[2] ; Cardoso, Daniel R. ^[1]

Affiliation

^[1] Univ Sao Paulo, Inst Quim Sao Carlos, BR-13560970 Sao Carlos, SP - Brazil

^[2] Univ Copenhagen, Dept Food Sci, DK-1958 Frederiksberg C - Denmark

• Document type: Journal article
• Source: Journal of Agricultural and Food Chemistry; v. 62, n. 5, p. 1153-1158, FEB 5 2014.
• Web of Science Citations: 4

Abstract

The reaction of the fresh meat pigment oxymyoglobin, MbFe(II)O-2, 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-2 by (3)Rib is (3.0 +/- 0.5) x 10(9) L.mol(-1).s(-1) and (3.1 +/- 0.4) x 10(9) L.mol(-1).s(-1) for MbFe(III) in phosphate buffer of pH 7.4 at 25 degrees 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-a = (1.2 +/- 0.2) x 10(4) mol.L-1 with Delta H degrees = -112 +/- 22 kJ.mol(-1) and Delta S-circle = -296 +/- 75 J.mol(-1).K-1. For meat, riboflavin is concluded to be a photosensitizer for protein oxidation but not for discoloration. (AU)

• FAPESP's process: 11/18215-8 - Advanced fluorescence microscopy: nano and micro analysis of chemical and biological systems
• Grantee: Marcelo Henrique Gehlen
• Support Opportunities: Regular Research Grants