While the addition of 50 mM KCl, did not improve NMP formation, a 20-fold increase in HsAK lead to an increased substrate conversion of dAdo, AraA and FAdo (Figure ). A combination of KCl addition and increased enzyme concentration further improved NMP formation for dAdo and FAdo. In accordance with literature data, no significant conversion of AraA was observed, which confirms the results by Yamada et al., who showed HsAK activity towards AraA to be max.