Forget, S.; Krawczyk, M.; Knight, A. M.; Ching, C.; Copeland, R.; Mahmoodi, N.; Mayo, M.; Nguyen, J.; Tan, A.; Miller, M. G.; Vroom, J.; Lutz, S.

Enzymatic DNA synthesis, using stepwise nucleotide addition catalyzed by template-independent polymerases, promises higher efficiency, quality, and sustainability than today\'s industry standard phosphoramidite-based processes. We report on the directed evolution of a terminal deoxynucleotidyl transferase that uses 3\'-phosphate blocked dNTPs to control the polymerization reaction and demonstrates high activity for these modified substrates and improved template promiscuity and thermostability.