The Reduction of Chromate Solutions by x-Rays<sup>1</sup>

Fricke, Hugo; Brownscombe, E.R.

doi:10.1021/ja01333a021

Cited by 37 publications

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“…It is probable that all substances of organic nature, and inorganic substances which are less inert than, for example, NaCl, will produce this effect. Some investigators of radiation effects on substances other than enzymes have made similar observations [Stenstrom & Lohmann, 1931;1933;Fricke & Brownscombe, 1933;Fricke & Washburn, 1932]. This inhibition of the radiation effect by the presence of other substances, i.e.…”

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confidence: 62%

The effect of X-rays on the conjugated protein d-amino-acid oxidase

Dale

1942

Biochemical Journal

111

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In a previous paper [Dale, 1940] the effect of X-rays on crystalline carboxypeptidase and polyphenol oxidase was investigated mainly in regard to the radiosensitivity of these enzymes as a function of their concentration. One of the findings of this investigation was that enzymes are affected by reasonably small doses of X-radiation. Since their high chemical activity allows the measurement of radiation effects on them in concentrations as low as those in which they occur in living matter, they are well suited for a more differentiating examination of their radiosensitivity at such concentrations.The work of Theorell [1937] and Warburg & Christian [1938] has established that a number of enzymes consist of conjugated proteins, and' are separable into a chemical compound of a relatively low molecular weight (prosthetic group sometimes called. coenzyme) and a highly specific protein, both of which are necessary for enzymic activity. There is, therefore, an opportunity of measuring the effect of radiation'on these components singly, together, and in combination with the substrate and other compounds.oc-Amino-acid oxidase [Krebs, 1933, 1, 2;1935], as one of those enzymes whose prosthetic group and specific protein can be separated, has been chosen as the subject of this investigation. Also its prosthetic group, alloxazinadeninedinucleotide, is of nucleotide nature and this forms a first step to the study of the radiosensitivity of nuciear substance on which attention has been focused for a long time.

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confidence: 62%

The effect of X-rays on the conjugated protein d-amino-acid oxidase

Dale

1942

Biochemical Journal

111

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“…For example, the reduction of bichromate ions to chromic ions (35) and the oxidation of ferrous ions to ferric ions (36) by x-rays were found to be independent of temperature (to within a few per cent) between 5 and 50°C. A moderate temperature coefficient for the inactivation of trypsin solutions by x-rays was found in this study when the medium in which the trypsin was irradiated was 0.005 N hydrochloric acid.…”

Section: Discussionmentioning

confidence: 99%

“…Ethanol also enhances some radiationinduced reactions. Among these are the oxidation of ferrous sulfate (43) and the reduction of ceric sulfate (44), potassium dichromate (35), and diphosphopyridine nucleotide (41). In these cases, however, no change in the reactiondose relationship was observed, the reaction remaining a linear function of time.…”

Section: Discussionmentioning

confidence: 99%

The Inactivation of Dilute Solutions of Crystalline Trypsin by X-Radiation

McDonald

1955

The Journal of General Physiology

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Previous studies in this laboratory (1) on the inactivation of dilute solutions of crystalline trypsin in 0.005 N hydrochloric acid by x-radiation at room temperature showed that the reaction yield, that is, the number of micromoles of trypsin per liter inactivated per 1000 roentgens (r), increases markedly as the initial concentration of trypsin is increased from 0.1 to 200 micromolar (~) . On the other hand, Dale and his coworkers (2) demonstrated that the reaction yield for the inactivation of aqueous solutions of crystalline carboxypeptidase by x-rays is constant for concentrations of enzyme between 6 and 600 /~M. Only a slight rise in the reaction field for the inactivation of aqueous solutions of crystalline pepsin by high voltage electrons was observed by Bellamy and Lawton (3) when the concentration of pepsin was increased from 2.8 to 140 ~s. These are the only pure enzymes that have been studied extensively over a wide concentration range.Fricke's observations (4) on the reactivity of hydrochloric acid in radiation studies raised the question whether the continuous rise in reaction field with increasing concentration of trypsin obtained in the previous studies (1) was due to the presence of hydrochloric acid in the solutions. A detailed study was therefore made of the inactivation by x-radiation of dilute solutions of trypsin in diverse media under various experimental conditions. This showed that the chemical nature of the medium in which the trypsin is irradiated markedly affects the reaction field. When solutions of trypsin of various concentrations in 0.005 N hydrochloric, sulfuric, or nitric acid were irradiated, the reaction yields were found to increase as the concentration of enzyme was increased. The rise was less pronounced in the presence of sulfuric or nitric acid, however, than in the presence of hydrochloric acid. With concentrations of trypsin between 1 and 10/~M, the reaction yields obtained in 0.005 N hydrochloric acid

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“…The dosage rate at the position of the solutions being irradiated was determined before and after each period of irradiation with a calibrated 250 r Victoreen condenser r-meter (Glasser-Seitz type), and was usually of the order of 450 r per minute. Determinations of the dosage rate by chemical dosimetry (20,21) showed (22) that 90 per cent of the administered radiation was utilized by the solutions.…”

Section: Inactivation O1 ~ Trypsin By X-radiationmentioning

confidence: 99%

The Inactivation of Dilute Solutions of Crystalline Trypsin by X-Radiation

McDonald

1954

Journal of General Physiology

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Numerous investigators (1) have shown that exposure of solutions of enzymes to ionizing radiation results in loss of enzymatic activity. Dale and his coworkers (2, 3) demonstrated that the enzyme molecules are not inactivated by x-rays directly, but indirectly, through reaction with intermediate products formed by the action of the ionizing radiations on the solvent. The hypothesis of the indirect action of radiation was originally proposed and developed in great detail by Risse (4) and Fricke et al. (5)(6)(7), who used principally inorganic and simple organic compounds as their test materials. Such indirect reactions are usually characterized (6, 8) by a reaction yield which is independent of the concentration of the solute when this is above a certain value characteristic of the system. For example, the ionic yield for the inactivation of solutions of carboxypeptidase by x-radiation was found (9) to be constant for all concentrations greater than 6 X 10 -6 M. This, however, is the only pure enzyme for which published data covering a wide range of concentrations are available. When preliminary experiments in this laboratory (10) on the inactivation of solutions of crystalline trypsin ranging from 1 X 10-7 to 2 X 10 -4 ~ demonstrated that the reaction yield increased continuously with increasing concentrations of trypsin, a detailed study of the phenomenon was undertaken. Some of the results of these investigations, using 0.005 ~r hydrochloric acid as the solvent, are presented in this paper. The results of experiments in which other solvents were used will be published subsequently. Materials and MethodsPreparation of Trypsin.--The trypsin used throughout this work was crystallized by the procedure of McDonald and Kunitz (11) from crystalline trypsinogen that

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The Reduction of Chromate Solutions by x-Rays¹

Cited by 37 publications

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The effect of X-rays on the conjugated protein d-amino-acid oxidase

The effect of X-rays on the conjugated protein d-amino-acid oxidase

The Inactivation of Dilute Solutions of Crystalline Trypsin by X-Radiation

The Inactivation of Dilute Solutions of Crystalline Trypsin by X-Radiation

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The Reduction of Chromate Solutions by x-Rays1

Cited by 37 publications

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The effect of X-rays on the conjugated protein d-amino-acid oxidase

The effect of X-rays on the conjugated protein d-amino-acid oxidase

The Inactivation of Dilute Solutions of Crystalline Trypsin by X-Radiation

The Inactivation of Dilute Solutions of Crystalline Trypsin by X-Radiation

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The Reduction of Chromate Solutions by x-Rays¹