Decrease of Radiation Damage to Proteins by Sulfhydryl Protectors

Abstract

The influence of known chemical protectors in reducing the radiation to hemoglobin, cytochrome c, and ovalbumin was investigated. The protein solutions (0.1%) with or without [long dash]SH compounds 1 x 103 M cysteine, 2-amino-ethylisothiuronium bromide HBv (AET) and 2-mercaptoethoxylamine HC1 (MEA) were prepared in demineralized water, and pH adjusted to 7. Amino acids in the proteins were analyzed by paper chromato-graphy after acid hydrolysis. Aerobic irradiation causes more destruction of amino acids than anaerobic. Under anaerobic condition, cysteine, MEA and AET offer considerable protection to the radio-labile amino acids, however, the protective effect is not specific for any particular amino acid. The observations indicate that the [long dash]SH compounds may be functioning by (1) induced anaerobiosis, (2) free radical scavenger effects, (3) capacity to form mixed disulfide, and (4) repair of chemical damage.