Formation of ortho-tyrosine by radiation and organic solvents in chicken tissue.

Fresh chicken breast and beef incubated in water were found to contain no o-Tyr at the current levels of detection (0.1 ppm) by capillary gas chromatography/mass spectrometry and selective ion monitoring. In contrast, samples incubated at 37 degrees C in the presence of ethanol, benzene, or carbon tetrachloride (used in fat extraction) contained large quantities (2.5-5.1 ppm) of o-Tyr. No o-Tyr was detected in the water-insoluble fraction of meat treated with carbon tetrachloride after triple extraction by water. However, reaction of radiation generated .OH in gamma-irradiated fresh chicken tissue with endogenous phenylalanine yields o-Tyr with a linear yield-dose response in both water-soluble and -insoluble tissue fractions. Nonradiolytically generated .OH is suggested to be formed through a mitochondrion-mediated Haber-Weiss reaction in association with water-soluble proteins since the yields of o-Tyr in beef, a tissue with a higher mitochondrial content, are four times greater than in the chicken breast tissue.