Optically detected magnetic resonance of the phosphorescent bases of XXXX valine-specific transfer ribonucleic acid.

@entity71196 @entity71197 @entity1025 @entity35343 @entity20101 @entity526
Phosphorescence spectroscopy and optical detection of triplet state magnetic resonance (ODMR) spectroscopy have been used to characterize bases that contribute to the phosphorescence emission of @entity526 valine-specific transfer ribonucleic acid. When it is excited with 335-nm light, a short-lived phosphorescence with an origin near 435 nm is observed and is assigned to @entity20101 ( @entity71196 ) at position 8 of the tRNA sequence. With excitation at 290-300 nm, a structured, long-lived phosphorescence is observed with an origin near 380 nm, in addition to the s4U phosphorescence. Comparison was made of the phosphorescence and ODMR spectra between @entity1025 -containing and @entity1025 -free tRNA samples. The s4U phosphorescence of the @entity1025 -containing sample is more structured, and the peak is blue shifted relative to the @entity1025 -free sample. Both samples give a single low-frequency (ca. 2.9 GHz) ODMR signal, but the high-frequency signal region (ca. 19-20 GHz) is structured. The @entity1025 -containing sample has a partially resolved group of lines centered at 19.3 GHz, whereas the @entity1025 -free sample has two broad bands centered at 19.2 and 20.0 gHz. The differences are attributed to effects of @entity1025 on the tRNA conformation. The ODMR signals observed by monitoring the long-lived phosphorescence are assigned to a @entity35343 , possibly @entity71197 in the anticodon.
