Patent ID: 7303897

Claim:
A method of obtaining polynucleotide fragments for use in polynucleotide shuffling, comprising: (a) obtaining a library of mutant polynucleotides from a parental polynucleotide by mutagenesis; (b) denaturing and hybridizing said mutant polynucleotides to form heteroduplex polynucleotides; (c) cleaving said heteroduplex polynucleotides by using proteins of a polynucleotide repair system which cleave mismatched base pairs; (d) denaturing said cleaved heteroduplex polynucleotides to obtain said polynucleotide fragments; and (e) recovering said polynucleotide fragments, wherein before exposing said heteroduplex polynucleotide to said polynucleotide repair system, formation of said heteroduplex polynucleotide is promoted by increasing the number of the parent polynucleotides in said library relative to other polynucleotides in said library.