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.
Karam
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Center for Radiation Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899.
Simic
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MG
D000818:Animals; D002417:Cattle; D002645:Chickens; D003037:Cobalt Radioisotopes; D004307:Dose-Response Relationship, Radiation; D005609:Free Radicals; D006878:Hydroxides; D017665:Hydroxyl Radical; D013058:Mass Spectrometry; D009132:Muscles / Q000528:radiation effects*; D010649:Phenylalanine / Q000528:radiation effects; D012997:Solvents; D014443:Tyrosine / Q000032:analysis*
D003037:Cobalt Radioisotopes; D005609:Free Radicals; D006878:Hydroxides; D012997:Solvents; D017665:Hydroxyl Radical; D014443:Tyrosine; D010649:Phenylalanine; C026741:2-tyrosine