Exposure of protein to oxidizing lipid induces fluorescence with excitation wavelengths of 350–360 nm and emission wavelength of 420–430 nm. This fluorescence was studied in freeze‐dried emulsions of methyl linoleate with chicken egg lysozyme and other proteins, and in solution with amino acids and several aldehydes. Generation of this fluorescence was found to depend on the reaction of amines with 2, 4‐decadienal or one of its breakdown products. Evidence was found suggesting that Schiff base formation of protein lysyl amines with conjugated dicarbonyls other than malonaldehyde is responsible for the fluorescence generated in the lysozymemethyl linoleate system.

Proteins in contact with peroxidizing lipids undergo various degradative reactions, including polymerization. Reaction of lysozyme with peroxidizing methyl linoleate at a water activity of 0.75 causes polymerization and partial denaturation of the protein. Polymerization occurs by addition of monomers, both native and denatured. The partial denaturation is probabl; due to the opening of a disulfide bond and occurs independently of\polymerization. This denatured fraction as well as dimer and trimer fractions was isolated and characterized with respect to enzymatic activity, tryptophan content, molecular weight, hydrodynamic volume, and circular dichroism.

No abstract

No abstract

No abstract