Hi,

If you want only one mutation, I suggest you to use pfu ultra high fidelity DNA polymerase from agilent. it is error rate is lower than pfu and also Taq polymerase. Otherwise you can not know which mutation effects your results.

Good luck

You have to examine if is due to error by Taq pol or it is due to polymorphism. Error you can check by including a known DNA also when you do amplification or using pfu as suggested to you by Miss Ozen. See if undesired mismatch does not change amino acid then go ahead with your experiment.

I think you have to use high fidelity mutagenesis kit like mutagenesis basal kit PrimeSTAR max.

PCR condition should also be optimized.