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

Abstract

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.

Genomic instability and bystander effects induced by high-LET radiation

“…As early as the 1940s, there were reports that the inactivation of biological entities may be brought about equally by ionizations produced within the entity, or by the ionization of the surrounding medium (Dale, 1940(Dale, , 1942(Dale, , 1943Lea et al, 1944). Kotval and Gray (1947) had shown that a-particles which pass close to the chromatid thread, as well as those which pass through it, have a significant probability of producing chromatid and isochromatid breaks or chromatid exchanges.…”

Research and Development of Radioprotective Agents: A Mini-Review

“…RAs could potentially counteract radiation effects from accidental or deliberate exposure hence they are also called radiation counter-measures [4] . The term of RA together with radioprotection was first introduced by Dale in 1942 during his studies on enzymes as indicative molecules [5] . Then in 1949, Patt and his co-workers were the first to investigate the radioprotective effect of amino-acid cysteine against lethal doses of X-rays according to the documented records [6,7] .…”

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

“…In the latter case, the inactivation is apparently due to reaction with the radiation products of water. The composition of the medium is of great importance here since the addition of other solutes will result in competition for these radiation products, effectively lowering the number available for reaction with the enzyme (24)(25)(26). The significance of this protective effect, although amply demonstrated in many studies, has not been sufficiently appreciated by many radiation experimenters, particularly with respect to the precautions that must be taken to avoid unintentional addition of substances other than the one being studied.…”