Patent ID: 7402383

Claim:
A process for preparing a population of variant polynucleotides comprising at least one polynucleotide having a desired property, comprising: (a) subjecting a starting population of polynucleotides comprising at least two different mutants of a parental polynucleotide to separate PCR's to result in products of the PCR's, wherein the at least two different mutants were selected for the desired property: (i) a first set of at least two PCR's, which are performed separately from each other, with each PCR using a forward mutation-specific primer which hybridizes to a mutated position in a mutant of the starting population and a reverse universal primer to generate a first common end for the first set of PCR's, (ii) a second set of at least two PCR's, which are performed separately from each other, with each PCR using a forward universal primer to generate a second common end for the second set of PCR's and a reverse mutation-specific primer which hybridizes to a mutated position in a mutant of the starting population, and (iii) optionally a third or more PCR with suitable forward and reverse primers; (b) assembling the resulting products of the PCR's using a polymerase to obtain said population of variant polynucleotides, wherein the variant polynucleotides differ in at least one position from the parental polynucleotide; and (c) optionally amplifying the population of variant polynucleotides.