The nucleotide sequences of the first 422 base pairs from the left-hand end and the first 274 base pairs from the right-hand end of phi 29 DNA were determined by using the chemical degradation method of Maxam and Gilbert. The data indicate that phi 29 DNA has inverted terminal repetitions that are six base pairs long 5' (-A-A-A-G-T-A-). No perfectly self-complementary sequence exists within the terminal regions of phi 29 DNA, suggesting that DNA replication via a self-priming mechanism is improbable. The putative early promoter sequences were found in both ends of the phi 29 DNA. The results of the sequence determination are discussed in relation ship to models proposed for the mechanism of replication of linear DNA molecules.
