Total synthesis of the structural gene for the precursor of a tyrosine suppressor transfer RNA from Escherichia coli. 6. Synthesis of the deoxyribopolynucleotide segments corresponding to the nucleotide sequence 100-126.

Chemical syntheses of the tridecanucleotide, d(G-C-T-T-C-C-C-G-A-T-A-A-G), the dodecanucleotide, d(G-C-T-C-C-C-T-T-A-T-C-G), the decanucleotide, d(G-G-A-G-C-A-G-G-C-C), the nonanucleotide, d(T-A-C-T-G-G-C-C-T), and the hexanucleotide, d(G-G-A-A-G-C), are described. Together, these syntheses represent the nucleotide sequence 100-126 of the DNA corresponding to the Escherichia coli tyrosine tRNA precursor. The synthesis of the dodecanucleotide d(G-C-T-C-C-C-T-T-A-T-C-G), was accomplished by the condensation of the previously described protected nonanucleotide, d[(MeOTr)ibG-anC-T-anC-anC-anC-T-T-bzA], with the trinucleotide block d[pT-anC-mbG(Ac)]. Synthesis of the other segments involved stepwise condensations to the 3'-OH group of growing oligonucleotide chains, starting with suitably protected deoxyribonucleosides and using protected mono-, di-, and trinucleotides as the incoming blocks. The final products, after deprotection, were purified by anion exchange chromatography and characterized. The synthesis of this part of the DNA was planned so that only a hexanucleotide segment is used to go up to the 3'-end (nucleotide 126) of the DNA and, therefore, it is amenable to elongation by chemical methods when the nucleotide sequence of the several nucleotides beyond this end becomes known.