T7 DNA polymerase

A method for determining the nucleotide base sequence of a DNA molecule, comprising:

• annealing said DNA molecule with a primer molecule able to hybridize to said DNA molecule;
• incubating separate portions of the annealed mixture in at least four vessels, each vessel containing four different deoxynucleoside triphosphates, a processive T7-type DNA polymerase, wherein said polymerase remains bound to said DNA molecule for at least 500 bases before dissociating in an environmental condition used in the extension reaction of a DNA sequencing reaction, said polymerse having less than 500 units of exonuclease activity per mg of said polymerase, and one of four DNA synthesis terminating agents which terminate DNA synthesis at a specific nucleotide base, wherein each said agent terminates DNA synthesis at a different nucleotide base, and
• separating the DNA products of each incubating reaction according to their size, whereby at least a part of the nucleotide base sequence of said DNA molecule can be determined.