Ultraviolett-inaktivierung der phenylalanin- und lysinspezifischen Transfer-Ribonucleinsäuren

Abstract

Ultraviolet-inactivation of phenylalanine and lysine-specific transfer ribonucleic acids The transfer of t-RNA-bound lysine to the growing peptide chain was studied in detail (Figs. 1 and 2). Besides oligo- or polylysine, oligo- or polylysyl t-RNA's are formed as transfer products. The conditions of their formation were examined. Oligo- or polylysyl t-RNA's were characterized by the kinetics of their alkaline hydrolysis (Fig. 3). Acceptor activities of uncharged s-RNA for phenylalanine and lysine and transfer activities of phenylalanyl and lysyl t-RNA's (charged prior to irradiation) were measured as a function of the ultraviolet-dose (280 mμ) in several experiments (Fig. 4). Assuming that averaging of the values is permissible, the following conclusions were drawn: For both, phenylalanine and lysine, acceptor activity of uncharged t-RNA and transfer activity of charged t-RNA have the same ultraviolet-sensitivity. The acceptor and transfer activities for lysine are destroyed twice as fast as for phenylalanine. The formation of oligo- or polylysine on the one hand and of oligolysyl t-RNA on the other hand are affected at the same rate. The results suggest that ultraviolet-light alters regions in the t-RNA molecule, which are important both for enzyme recognition and for template recognition.