Penicillin G acylase-based stationary phases: analytical applications.

A review of Penicillin G Acylase (PGA)-based stationary phases is given, focusing on immobilisation methods, selection of immobilisation material and applications in chiral liquid chromatography. Two immobilization methods, namely "in situ" and "in batch" techniques, are described for the immobilisation of PGA on silica supports. Microparticulate and monolithic silica, both functionalized with aminopropyl- and epoxy-groups, were used in the development of the PGA immobilised enzyme reactor (IMER). The best results, in terms of PGA immobilised amount and enzyme activity, were obtained with the "in situ" immobilisation on epoxy monolithic silica. The use of PGA columns as enzyme reactors for the preparation of 6-APA and for the production of enantiomeric pure drugs in a one-step reaction in described. The review also covers the application of PGA-columns as chiral stationary phases for the separation of acidic enantiomers. An on-line chromatographic system based on the PGA-IMER combined with a switching valve to an analytical column is also described as a highly efficient tool to study the enantioselective hydrolyses properties of PGA. Finally a molecular modelling study is reported with the aim to give more insights into PGA-substrates interactions and to expand the application of these stationary phases as a chiral biocatalysts for pharmaceutical processes.