If the nick made by MutH is on the 5' end of the mismatch, either RecJ or ExoVII (both 5' to 3' exonucleases) is used.
Se a amosega feita por MutH está no extremo 5’ da discordancia, utilízase a exonuclease RecJ ou a ExoVII (ambas as dúas son exonucleases 5’-3’).