Amidase encapsulated in TTAB reversed micelles for the study of transamidation reactions

Abstract

Amidase, an amide hydrolase enzyme (E.C.3.5.1.4) with acyl transferase activity, was encapsulated in a reversed micellar system composed of the cationic surfactant tetradecyltrimethyl ammonium bromide (TTAB) in heptane/octanol (80/20%) and phosphate buffer at w0 11. The reaction used to study the effect of the reversed micellar system on the enzyme behaviour was a transamidation reaction. The effect of surfactant concentration, buffer molarity and pH on the enzyme kinetics was evaluated. Both initial velocities and product yield were measured. The results indicated that a high initial velocity of hydroxamic acid synthesis and also the highest yield (98%) were obtained using the lowest pH value. The effect of TTAB concentration was dependent on the buffer molarity used. The effect of buffer molarity on reversed micelle dimensions was analysed by light scattering. These results showed that the buffer molarity had a strong influence on the reversed micelle radius that correlated with enzyme activity.