Purification and characterization of a novel 5' exodeoxyribonuclease from the yeast Saccharomyces cerevisiae.

We have isolated from yeast cells an exonuclease which preferentially attacks double-stranded DNA from the 5' ends producing 5'-mononucleotides as reaction products. A second typical product is a full-length single-stranded DNA complement, suggesting that the enzyme hydrolyzes one DNA strand in a processive manner before it associates with another DNA substrate to initiate a new reaction cycle. Its biochemical properties suggest that the enzyme is unlike the yeast exonucleases which have been reported so far. However, the new exonuclease is strikingly similar to the well characterized 5' exonuclease of bacteriophage lambda.