Abstract
Lactate dehydrogenase (LDH) exhibited over 2200% increase in activity following transient exposure to an ionic liquid (IL). 1-ethyl-3-methylimidazolium tetrafluoroborate and additives like water and flavin adenine dinucleotide (FAD) were used in parallel procedures. The effect on LDH activity in water has an optimum at a certain ratio protein/IL. The alterations are correlated with changes in the native structure of the enzyme and chaotropic character of the ions. FAD entrapped within the renatured enzyme (ME) may function as "molecular wire" enhancing kinetics of electron transfer. The novelty of this approach is using transient exposure to IL to enhance enzyme activity in an environmentally-and enzyme-friendly procedure. Altered LDH showed catalytic activity after one year in storage. A biosensor for lactate analysis was built using the ME. It showed catalytic effect and linear response as a function of lactate concentration. The value of the oxidation current was practically constant for 7 days.