Methods for producing proteins which bind to predetermined antigens

A method for producing a synthetic antibody that binds to an antigen, comprising:

• a. constructing a plurality of synthetic genes, each of said synthetic genes comprising a predetermined nucleotide region encoding the framework regions of portions of the heavy chain of an antibody, another predetermined nucleotide region encoding the framework regions of portions of the light chain of an antibody, and an undetermined nucleotide region which contains a random sequence of nucleotides, said undetermined nucleotide region being synthesized by stepwise addition of nucleotides selected at random from a mixture of nucleotides;
• b. expressing a plurality of proteins encoded by the plurality of synthetic genes from step (a), in microorganisms having inserted therein vectors comprising said synthetic genes;
• and
• c. contacting said plurality of proteins with the antigen to obtain said synthetic antibody binding to the antigen.