Patent ID: 7056661

Claim:
A method of obtaining nucleotide sequence information for a target nucleic acid molecule having a plurality of nucleotide bases, said method comprising: providing a single complex of a nucleic acid polymerizing enzyme and the target nucleic acid molecule oriented with respect to each other in a position suitable to add a nucleotide analog at an active site complementary to the target nucleic acid, wherein the complex is immobilized to a solid support; providing a plurality of types of nucleotide analogs that lack a blocking substituent proximate to the active site, each type of nucleotide analog being complementary to a different nucleotide in the target nucleic acid and having a different detectable moiety, and polymerizing a nucleotide analog at the active site, wherein the added nucleotide analog is complementary to the nucleotide of the target nucleic acid and is capable of polymerization with a subsequent nucleotide analog; identifying the nucleotide analog added at the active site as a result of said polymerizing by detecting its detectable label, wherein said identifying is carried out by directing activating radiation to a region corresponding to the active site and detecting the detectable label from the nucleotide analog added to the active site by a technique which reduces background noise resulting from free unpolymerized nucleotide analogs; and repeating, with the complex immobilized to the solid support, said providing a plurality of types of nucleotide analogs, said polymerizing, and said identifying, so that nucleotide analogs added at downstream active sites are identified and, as a result, nucleotide sequence information for the target nucleic acid is determined.