CXII. Total synthesis of the structural gene for an alanine transfer RNA from yeast. Enzymic joining of the chemically synthesized polydeoxynucleotides to form the DNA duplex representing nucleotide sequence 1 to 20

The DNA duplex (designated A]) corresponding to the nucleotides 1 to 20 of the major yeast alanine transfer RNA (Fig. 1) has been synthesized. The first step involved the T4 ligase-catalyzed joining of d-(5′-³²P)-C-C-G-G-A-A-T-C (segment 4, Fig. 1) to the dodecanucleotide, d-(5′-OH)-T-G-G-T-G-G-A-C-G-A-G-T (segment 1, Fig. 1), in the presence of the complementary decanucleotide d-(5′-OH)-C-C-G-G-A-C-T-C-G-T (segment 3, Fig. 1). The resulting icosanucleotide, d-(5′-OH)-T-G-G-T-G-G-A-C-G-A-G-T-C-C-G-G-A-A-T-C, was isolated free from the decanucleotide (segment 3). The synthesis of A] was then completed by the ligase-catalyzed joining of 5′-³²P or ³³P-labeled hexanucleotide d-(5′-P)-C-C-A-C-C-A (segment 2) to the 5′-³²P or ³³P-labeled decanucleotide, d-(5′-P)-C-C-G-G-A-C-T-C-G-T (segment 3), in the presence of the above icosanucleotide.