Cryo-enzymatic synthesis of kyotorphin in saline environments

The effect of six different alkali halides (LiCl, NaCl, KCl, LiBr, NaBr and KBr) on kyotorphin ethyl ester synthesis catalyzed by alpha-chymotrypsin has been studied in aqueous media at low temperature (3 degrees C). The results showed an enhancement on the synthetic activity of the enzyme by the presence of salts, proportionally to salt concentration. Water activity was shown as a key parameter in the control of the enzyme synthetic action in the saline media, being the influence of the assayed salts independent of the nature of ions. In all cases, the decrease in the reaction temperature to subzero values (-20 degrees C) reported a proportional increase in the selectivity of the peptide synthesis reaction.