THE INFLUENCE OF IONIZING RADIATION ON THE KINETICS OF ENZYME REACTIONS (in German)
Studies were conducted on the effects of radiation on diphosphopyridine nucleotide (DPN)-coupled enzyme reactions in vitro, including those catalyzed by alcohol dehydrogenase (ADR), glutamic dehydrogenase (GDH), lactic dehydrogenase (LDH), and malic dehydrogenase (MDH). In contrast to results of earlier studies, radiation was found to affect the kinetics of these enzyme reactions. It was shown that the reaction catalyzed by ADR is inhibited during irradiation with 15,000 r/min, that this inhibition is much greater than inactivation of ADH by prior irradiation of the enzyme, and that the ADR-catalyzed reverse reaction is accelerated by irradiation. Similar results were found with LDH and MDH. Since irradiation of the enzyme alone causes little inactivation, DPN and DPNH were irradiated to determine the cause for the greater sensitivity of the entire system. It was shown that the coenzyme is irreversibly altered by irradiation, approximates 30% inactivation by 47,000 r. This inactivation was more evident in the presence of ADR than MDH, LDH, and GDH. Irradiation of DPNH caused, in addition to irreversible degradation, conversion to DPN. This reversible oxidation to DPN could be depressed by the presence of glycine, cysteine, and small amounts of ethanol, whereas it was stimulated by a-ketoglutarate and acetaldehyde. Hence, it appeared to occur via a radiation-induced chemical reaction. (H.H.D.)
- Research Organization:
- Institut fur Strahlenschutzforschung, Nuremburg
- NSA Number:
- NSA-17-033625
- OSTI ID:
- 4664448
- Journal Information:
- Aerztliche Forschung (West Germany) Discontinued, Vol. Vol: 16; Other Information: Orig. Receipt Date: 31-DEC-63
- Country of Publication:
- Country unknown/Code not available
- Language:
- German
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