STRUCTURAL STUDIES ON TRANSFER RIBONUCLEIC ACID .I. LABELING OF EXPOSED GUANINE SITES IN YEAST PHENYLALANINE TRANSFER RIBONUCLEIC ACID WITH KETHOXAL

Yeast phenylalanine transfer ribonucleic acid was labeled with tritiated kethoxal in the presence of Mg2+ at 37°. After 30-min reaction time, only two sites were labeled to a significant extent. These were the guanines at positions 20 and 34 of the transfer ribonucleic acid chain. This labeling pattern is consistent with the “folded cloverleaf” model recently proposed by Cramer et al. (Cramer, F., Doepner, H., v. d. Haar, F., Schlimme, E., and Seidel, H. (1969), Proc. Natl. Acad. Sci. U. S. 67,1384). © 1969, American Chemical Society. All rights reserved.