Amino-acids, acyl-amino-acids, dipeptides, acyl-dipeptides, and derivatives of these compounds

Abstract

THE present study was undertaken to gain some information as to the nature of the effect of radiant energy on the matter of living cells.Solutions of several amino-acids and of a large number of derivatives of amino-acids and dipeptides, the absorption curves of which are given in the foregoing paper, were submitted to the action of cathode rays and of ultraviolet light.Absorption measurements were made on the solutions in order to see whether the compounds had under- gone any change under the influence of the radiations used.That such was invariably the case can be seen from the figures presented here.The absorption curve of any irradiated solution, when compared with that of the original solu- tion, was usually found to lie on the side of the greater wave-lengths.This was indicative of the occurrence of some deep-seated reactions.It may be recalled that ac-amino-acids are decomposed under the influence of sunlight in the presence of oxygen.The photochemical reaction has been summarily represented by the following equation:This photo-oxidation takes place in aqueous solution in the presence of metal salts [Neuberg, 1908; 1910] or metal oxides [Gopala & iDhar, 1934], and also in the absence of any such catalysts [Ganassini, 1912; 1913].Peptones and proteins [Neuberg, 1908; 1910] also yield aldehydes, ammonia and carbon dioxide, a fact which can be explained only by assuming that at some stage of the process hydrolysis of the peptide linkages takes place.Having exposed various amino-acids to the light of a mercury vapour quartz lamp, Lieben & Urban [1931] reported that the rate of deamination varies, as