Abstract: In an effort to investigate the aggregation mechanism of sarcoplasmic proteins under oxidative stress induced by peroxyl radicals (ROO·), sarcoplasmic proteins isolated from rabbit meat was oxidized by ROO· produced by thermal decomposition of 2,2’-azobis(2-amidinopropane) dihydrochloride (AAPH) and evaluated for the contents of metmyoglobin (MetMb), Mb(IV)=O, protein carbonyl and total sulfhydryl group, surface hydrophobicity, particle size, turbidity, solubility, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and intrinsic fluorescence characteristics. Both the MetMb and Mb(IV)=O contents significantly increased with AAPH concentration (P < 0.05), and so did the protein carbonyl content (P < 0.05), while the total sulfhydryl content significantly dropped (P < 0.05). The results of intrinsic fluorescence spectra and surface hydrophobicity revealed that ROO· caused protein unfolding and conformational changes in sarcoplasmic proteins. SDS-PAGE analysis indicated that ROO· could lead to protein crosslinking via disulfide bonds. The particle size and turbidity showed a gradual rising trend, revealing that ROO· could induce protein aggregation. Both hydrophobic interaction and disulfide bond cross-linking were the major driving forces for the aggregation of sarcoplasmic proteins induced by ROO·. ROO· could not only directly induce the aggregation of sarcoplasmic proteins in rabbit meat but also promote their crosslinking and aggregation by inducing myoglobin oxidation.

Key words: rabbit meat; peroxyl radical; sarcoplasmic proteins; aggregation