The effect of U.V.‐light on some components of the nucleic acids. V. Reversibility of “the first irreversible reaction” under special conditions

Abstract

Abstract The extent to which the extinction of thymine and orotic acid decreases on irradiation by U.V. light depends on the environmental conditions. Successive irradiations in different milieus ultimately lead to a degree of conversion which is wholly determined by the conditions during the last irradiation. Consequently it is possible to revert the substances that seem to have disappeared to the original products.