Conformational change in yeast tRNA^Asp

Abstract

SynopsisThe structure of yeast tRNAASp in aqueous solutions has been analyzed in the light of results obtained from Raman spectra recorded a t from 5 to 82OC and compared to those of' tRNAPhe. Firm evidence is given of a reversible conformation transition for tRNAAsp a t 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 tRNAASp, lie in a range of about 70°C, much higher than for tRNAPhe. This fact is interpreted by a higher ratio of G-C base pairs in tRNAASp.

New structures from the thermal rearrangement of polybutadiene revealed by 2D HSQC NMR

“…Another intermolecular reaction between a vinyl group and a 1,4-isomer with the formation of methyl group has been suggested by Golub et al [2], and other authors [12,13].…”

“…The PB sample was synthesized using sec-butyl lithium as an initiator. The structure of the PB sample was characterized by 13 C-NMR spectroscopy showing that it contains 33% of 1,4-cis, 59% of 1,4-trans, and 8% of 1,2-vinyl monomers. The number-average molecular weight of 7600 was determined by Size Exclusion Chromatography coupled with a laser detector.…”

“…Comparison of13 C NMR spectra (100 MHz, CDCl 3 , reference TMS) in the aliphatic region (from 5 to 48 ppm) and in the olefinic region (from 113 to 145 ppm) of 1,4-PB after heating at 260 C for 0 h, 1 h, 6 h, 12 h, 18 h, and 24 h (Y: decrease of signal intensity; [: increase of signal intensity).…”

Three-dimensional structure of yeast tRNAAsp. I. Structure determination

“…From one crystal form to the other this second binding site moves by more than 3 .~. This movement is related to a conformational change of the tRNA molecule (Huong et al, 1984).…”