Kinetic and Stability Studies of Penicillin Acylase in Reversed Micelles

Abstract

The main purpose of this work was to study the stability of a dimeric enzyme, penicillin acylase, in reversed micelles. Kinetic studies were carried out in order to understand the enzyme behaviour in reversed micelles. The enzyme activity profile as a function of the water content of the system exhibited three maxima at w₀ equal to 14, 20 and 23, which were assigned to the light sub-unit, to the heavy sub-unit and to the enzyme itself. The effect of AOT concentration on the activity of penicillin acylase was also studied and an increase in the surfactant concentration, at a constant w₀ was shown to produce an increase in enzyme activity. The influence of the water content (w₀), AOT and enzyme concentration on the enzyme stability in reversed micelles was then investigated.

Enzyme stabilisation by the addition of alcohols and sugars was examined and the sugar alcohol mannitol shown to provide an increase of more than 300% in the retention of activity.

Key Words:

• Penicillin acylase
• Oligomeric enzyme
• Reversed micelles
• Thermostability
• Stabilisation