Patent ID: 7244561

Claim:
A method for isolating a nucleic acid duplex comprising: (a) applying a sample comprising cells containing nucleic acid to a filter, wherein the nucleic acid comprises a nucleic acid duplex, whereby the cells are retained as a retentate and contaminants are removed; (b) lysing the retentate from step (a) while the retentate is retained by the filter to form a cell lysate containing the nucleic acid; (c) filtering the cell lysate with the filter to retain the nucleic acid and remove remaining cell lysate; (d) washing the nucleic acid retained by the filter with a solution having a pH of from 3 to 11 and comprising: (1) a soluble protein or mixture of proteins and (2) 0.1 mM to 10 mM divalent cations, wherein the nature and concentration of the protein or mixture of proteins is selected so that the solution inhibits heat denaturation of a nucleic acid duplex; (e) heating the nucleic acid duplex to an elevated temperature while retained by the filter; and (f) eluting the nucleic acid duplex, wherein the filter composition and dimensions are selected so that the filter retains the cells and the nucleic acid duplex.