Biochemical studies of radiation damage. I. Inactivation of the pH5 fraction in amino acyl sRNA synthesis in vitro and the binding of amino acids with protein and nucleic acid by gamma-ray irradiation.

Abstract

SummaryThe ph 5 enzyme fraction obtained from yeast cells was irradiated alone with gamma-rays. After the addition to a reaction mixture and incubation, the inactivation mode of the enzymatic activity of phenylalanyl sRNA synthesis in vitro was shown to be sigmoidal as a function of log dose. When the enzyme fraction plus the reaction mixture was irradiated, unusual bindings of amino acid with protein and sRNA occurred. The amino acids bound abnormally by irradiation were specifically limited to those having a resonance ring, or those containing sulphur atoms.