Conformational change in yeast tRNA^Asp

Abstract

Abstract The structure of yeast tRNA Asp in aqueous solutions has been analyzed in the light of results obtained from Raman spectra recorded at from 5 to 82°C and compared to those of tRNA Phe . Firm evidence is given of a reversible conformation transition for tRNA Asp at 20°C. This transition is observed for the first time in the tRNA series. The low‐temperature conformation appears to have a more regular ribose–phosphate backbone and a more effective G base‐stacking. This conformational change, which occurs essentially in the D loop, could be connected to the existence of two (A and B) crystal forms obtained depending on crystallization conditions. The melting temperatures, which are different for each base stacking in tRNA Asp , lie in a range of about 70°C, much higher than for tRNA Phe . This fact is interpreted by a higher ratio of G‐C base pairs in tRNA Asp .