Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


Partial digestion of native tRNA molecles with P(,1) nuclease under conditions which take advantage of the differences in kinetic parameters of this enzyme for various substrates has been performed. Under these conditions the two conformers of yeast tRNA(,3)('Leu) give different digestion patterns, indicating that P(,1) nuclease is sensitive to structural features of its substrate. Comparison of the digestion pattern of tRNA('Phe) from yeast with its known three-dimensional structure shows that stem and loop regions can be distinguished and that twelve of the twenty residues involved in tertiary hydrogen bonding interactions can be detected. Extrapolation of the tertiary structure of tRNA('Phe) to yeast tRNA(,3)('Leu)(N) is borne out by the digestion patterns of the D-arm, T-arm and anticodon loop, but results for the variable arm are difficult to interpret. The digestion pattern of yeast tRNA(,3)('Leu)(D) is compatible with models of its secondary structure. Populations of transfer RNA from human placenta and leiomyoma were compared by reversed-phase chromatography (RPC-5). The isoacceptors of tRN('Phe), tRNA('Ser), tRNA('Asp) and tRNA('Tyr) included extra species in the tumor tRNA population. Quantitative differences in the isoacceptors of tRNA('Lys) were observed between the two populations. These data are interpreted in terms of the theories about regulation of gene expression at the level of translation by transfer RNAs.