Direct cycle sequencing with delta Taq DNA polymerase.

The delta Taq DNA polymerase is a new, genetically modified version of standard Taq DNA polymerase which lacks the 5'-->3'-exonuclease activity. The present study was designed to investigate the use of delta Taq DNA polymerase for direct cycle sequencing. Results show that delta Taq DNA polymerase can be used for direct cycle sequencing of the PCR amplified DNA, either from an asymmetrically amplified template (by PCR), double stranded DNA template, PCR amplified DNA cloned into a plasmid vector or from a single stranded template. The primer to template ratio and number of cycles necessary for best sequence data have been determined. From these results we conclude that delta Taq DNA polymerase is a highly versatile enzyme which can be used for DNA sequence determinations by direct cycle sequencing.