THE USE OF STABILIZED PENICILLIN ACYLASE DERIVATIVES IMPROVES THE DESIGN OF KINETICALLY CONTROLLED SYNTHESIS

The advantages of the use of stabilised derivatives in the kinetically controlled synthesis catalysed by penicillin G acylase has been discussed. Stabilised derivatives were found to be less inhibited by the nucleophile than non-stabilised ones, improving in that way the reaction rate. Also, more resistance under unfavourable conditions (e.g. presence of methanol) was found using stabilised derivatives. Multipoint covalently attached derivatives prepared in the presence of penicillin sulfoxide showed the same hydrolytic/synthetic ratio as the non-distorted enzyme suggesting that the stabilisation strategy is able to increase the enzyme rigidity without promoting significant changes in the enzyme properties. In addition, the effect of the enzyme source was found to be significant: enzyme derivatives from Escherichia coli appeared to have better properties as catalysts of these reactions than enzyme derivatives of penicillin G acylase from Kluivera citrophila.