Patent ID: 7208268

Claim:
A method of identifying differences in expression of polypeptides between two samples, said method comprising: (a) providing one or more first arrays comprising one or more polypeptides from a first complex biological sample adhered to a first type of support; (b) providing one or more second arrays comprising one or more polypeptides from a second complex biological sample adhered to a second type of support; (c) exposing a peptide-nucleic acid coupled library comprising a plurality of members (i) to one of said first arrays at least one time to create a first product, said first product comprising one or more members of said peptid-nucleic acid coupled library that reversibly bind to said first array and (ii) to one of said second arrays at least one time to create a third product, said third product comprising one or more members of said peptide-nucleic acid coupled library that reversibly bind to said second array; (d) exposing said first product to one of said second arrays at least one time to create a second product, said second product comprising one or more members of said first product that do not bind to said second array and; (e) exposing said third product to one of said first arrays at least one time to create a fourth product, said fourth product comprising one or more members of said third product that do not bind to said first array, wherein a member of said peptide-nucleic acid coupled library in said second product binds to a polypeptide in said first biological complex sample that is expressed in a greater amount than in said second complex biological sample and a member of said peptide-nucleic acid coupled library in said fourth product binds to a polypeptide in said second biological sample that is expressed in a greater amount than in said first biological sample.