Date of Award

Spring 1993

Document Type


Degree Name

Master of Science (MS)


Chemistry & Biochemistry



Committee Director

Mark S. Elliot

Committee Member

Laura K. Moen

Committee Member

Roy L. Williams

Call Number for Print

Special Collections LD4331.B43 S26


The discovery of a base-exchange modification in the first position of the anticodon of four transfer RNA (tRNA) isoacceptor families has been shown to be correlated with a decrease in the rate of cell division in several tumorigenic tissues. This fact led to the hypothesis that wobbling in the anticodon might be a control point wich mediates the rate of translation. A suitable method for separation of different tRNA isoacceptor families had to be created in order to generate a means for quantitatively measuring degrees of this base modification in tRNA. Radio labelled amino acids were used to charge tRNA isolated from two chronic lymphocytic leukemia cell cultures (HL-60). In one culture the cells were exposed to 7-methyl guanine, an inhibitor of the enzyme responsible for the insertion of the modified base queuine into tRNA. The other culture was not treated with 7-methyl guanine, thus allowing a normal rate of base exchange to occur. The reaction mixtures were then injected in a W-Porex C-4 column, and analyzed by high pressure liquid chromatography (HPLC). Four different retention times were identified, corresponding to the four tRNA species undergoing queuine base-exchange, and levels of base modification in three of the four isoacceptor families in question were quantified, specifically tRNAHis, tRNATyr, and tRNAAsp. The results suggest that this technique has the potential to become a standard procedure for diagnosis of aberrant base modifications in tRNA. This methodology provides better resolution than previous methods utilized due to revised parameters. It is also innovative in that it uses one single matrix for both the separation of different tRNA isoacceptors and the resolution of queuine-modified molecules from unmodified species.


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