Photodynamic Action of Thiopyronine on Polyribosomes and Cell-free Protein Synthesis in Yeast

Abstract

The treatment of yeast [Saccharomyces cerevisiae] with thiopyronine (TP) caused a degradation of polyribosomes, even if the cells were not illuminated. No differences in the polyribosome profiles of illuminated and unilluminated cells was seen. In in vitro experiments, there was no degradation of polyribosomes caused by dark effect or photodynamic action. Cell-free protein synthesis was inhibited up to 75% by the photodynamic effect when the complete system was treated, but up to 40% when the polyribosomes or enzyme fraction were treated. Since the enzyme fraction contained aminoacyl-tRNA-synthetases and tRNA, it was necessary to investigate separately the effect of TP on the enzyme and the tRNA. The aminoacyl-tRNA-synthetase and not tRNA was effected by the photodynamic action in its biological activity.