Quantitative model of tryptophan radiation synthesis in water-accohol indole-alanine solution

Besides the theoretical value, the study of radiation-chemical carboxylation of the indole-alanine system is caused by the possibility of its use for obtaining an essential amino acid – tryptophan. In the previous paper an impact of the acceptors of charge − diphenyl and hydrogen peroxide – on the kinetics of radiolysis of the system: water, alcohol, indole, serine was studied. [1]. It was determined, that the solvated electron plays a decisive role in a mechanism of tryptophan formation. The purpose of this paper is to formulate a quantitative model of tryptophan radiation synthesis by the example of water-alcohol solution of the indole and alanine. The radiolysis was performed by γ–rays of the radioactive isotope 60-Сo at the UGU-420A facility under static conditions at the dose rate 1.2 Gy/s. The system in question, which consists of 0.1M of the alcoholic solution of indole and 0,1M of aqueous solution of alanine at the ratio 1:1, saturated with carbon and exposed to radiation treatment, was investigated by means of thin-layer chromatography for amino acids determining.

The error of determination was ± 5 %. By the method of ascending paper chromatography with subsequent quantitative determination, tryptophan was detected in the irradiated solution. The dependence of tryptophan concentration on a dose during radiation-chemical carboxylation in the indole-alanine system was demonstrated. Based on the obtained experimental and calculated values of radiation-chemical output of β-indolylmaleimide acid (tryptophan), theoretical model that satisfactorily describes the experimental data was established.

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