Patent ID: 7067284

Claim:
A method for producing an antibody combining site in a polypeptide comprising: a) inducing mutagenesis in a complementarity determining region (CDR) of an immunoglobulin light chain gene which comprises amplifying a CDR portion of the immunoglobulin gene by polymerase chain reaction (PCR) using a PCR primer oligonucleotide, said oligonucleotide having 3′ and 5′ termini and comprising: i) a nucleotide sequence at said 3′ terminus capable of hybridizing to a first framework region of the immunoglobulin gene; ii) a nucleotide sequence at said 5′ terminus capable of hybridizing to a second framework region of an the immunoglobulin gene; and iii) a nucleotide sequence between said 3′ and 5′ termini according to the formula: [NNK] n (SEQ ID NO:73) wherein N is independently any nucleotide, K is G or T, and n is 3 to about 24, said 3′ and 5′ terminal nucleotide sequences having a length of about 6 to 50 nucleotides, or an oligonucleotide having a sequence complementary thereto; b) isolating the amplified CDR to form a library of mutagenized immunoglobulin light chain genes; c) expressing the isolated library of mutagenized light chain genes in combination with one or more heavy chain genes to form a combinatorial antibody library of expressed heavy and light chain genes; and d) selecting species of said combinatorial antibody library for the ability to bind a preselected antigen.