Stability of the enzyme (S)-hydroxynitrile lyase from Hevea brasiliensis

Inactivation of the enzyme (S)-hydroxynitrile lyase from Hevea brasiliensis (rubber tree) was studied using three different buffers: sodium glutamate, sodium phosphate and sodium citrate. Inactivation follows a first order kinetics and was expressed by the half-life of the enzyme. From the inactivation at different temperatures, the inactivation energy was calculated for the different buffer systems; no significant difference could be found. Stability decreases rapidly with lower pH values in all three buffer systems and the enzyme is very unstable at pH 3.5. At pH 6.5 half-life increases with higher buffer concentrations in all three buffers whereas at pH 3.5 half-life decreases with higher buffer concentrations. Stabilisers improved the stability of the enzyme with increasing concentrations. (C) 1998 Elsevier Science B.V. All rights reserved.