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Effect of 60 Co γ Radiation on the Valyl-tRNA Synthetase Isolated from Chick Embryo Brain

1978; Taylor & Francis; Volume: 34; Issue: 4 Linguagem: Inglês

10.1080/09553007814550961

0020-7616

Erzsébet Bölöni, László Szabó,

ATP Synthase and ATPases Research

SummaryThe effect of 60Co γ irradiation on the activity of valyl-tRNA synthetase isolated from chick embryo brain was studied. The enzyme activity exponentially decreased in the dose range 10–200 krad. The first step of the enzyme action, i.e. the amino acid activation, was found to be less sensitive to irradiation than the whole reaction, the formation of valyl-tRNA. 2-Mercapto ethanol and/or glycerol had a significant radioprotective effect. The lesion caused by radiation in the enzyme was also influenced by its concentration during exposure (dilution effect). According to gel-electrophoretic experiments, no chain rupture occurred in the enzyme molecule. Not even a change in Km was observed; however, the maximum velocity of the reaction was found to decrease with increasing radiation dose.