Patent ID: 7632652

Claim:
A method of detecting in situ an immunohistochemical epitope or nucleic acid sequence of interest in a biological sample, comprising: binding an enzyme-labeled conjugate molecule to said epitope or sequence of interest; contacting said enzyme-labeled conjugate molecule with a redox-inactive reductive species that is a substrate for an enzyme of said enzyme-labeled conjugate and a soluble metal ion, wherein said enzyme is selected from the group consisting of alkaline phosphatase, acid phosphatase, alpha- and beta-galactosidases and esterases; and, wherein the enzyme of said enzyme-labeled conjugate converts said redox-inactive species to a redox-active species that reduces said soluble metal ion to an insoluble metal atom that precipitates at or about the point where said enzyme-labeled conjugate molecule is bound: and, detecting in situ said immunohistochemical epitope or nucleic acid sequence of interest in said sample by detecting the presence of said insoluble metal atom precipitated at or about the point where said enzyme-labeled conjugate molecule is bound to said immunohistochemical epitope or nucleic acid sequence.