Effect of bromination on the Amino acid-accepting activities of transfer ribonucleic acids

• Published in: Biochimica et biophysica acta. Specialized section on nucleic acids and related subjects Vol. 76; pp. 209 - 222
• Main Authors: Yu, C.T., Zamecnik, P.C.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 1963
• ISSN: 0926-6550; 1878-2256
• DOI: 10.1016/0926-6550(63)90034-3

1. 1. Bromine reacts with uridylic, cytidylic and, to a lesser extent, guanylic acid at room temperature and pH values of 5·7 and lower. Adenylic acid does not react with bromine appreciably under these conditions. 2. 2. Alkaline hydrolysis of transfer RNA, following bromination at room temperature and pH 5·7, indicates that bromine reacts rapidly with uracil and cytosine and much more slowly with guanine residues of transfer RNA under these experimental conditions. The extent of bromination during a given period of time is proportional to the concentration of bromine. By using a molar ratio of 1 bromine to 40 nucleotide residues of transfer RNA, approx. 1 uracil and 1 cytosine per 80 nucleotide residues of transfer RNA are brominated. 3. 3. At the above bromination level of 1 bromine to 40 nucleotide residues of transfer RNA, the inhibitory effects on the formation of phenylalanyl-, lysyl-, and valyl-RNA are 67, 32 and 16%, respectively. From this we conclude that the nucleotide sequence in transfer RNA responsible for recognition of phenylalanyl-RNA synthetase appears to consist of at least one bromine-sensitive residue, probably a pyrimidine, and thus differs from the AAA sequence suggested as the polynucleotide code for transfer of activated phenylalanine to the ribosomes.