ИСТИНА

Penicillin acylase (PA; EC 3.5.1.11) is widely used in pharmaceutical industry for the production of semi-synthetic β-lactam antibiotics. Other applications of the enzyme are peptide synthesis and resolution of racemates. PA was cloned from A.xylosoxidans, A.faecalis, A.viscosus, B.megaterium, B.badius, E.coli, K.criocrescens and P.rettgeri. PA from Alcaligenes faecalis (AfPA) was shown to surpass well-known enzyme from E.coli in pH optimum of activity and thermal stability. In this work the thermal stability of the wild-type (wt-AfPA) and permuted PA (pAfPA) from Alcaligenes faecalis was investigated. The wt-AfPA represents a heterodimer consisting of α- and β-subunit. The gene of wt-AfPA encodes a precursor polypeptide that undergoes two-step processing – transportation of the precursor to the periplasm followed by elimination of signal peptide, and excision of the spacer peptide between subunits. In our laboratory we constructed permuted pAfPA., which in contrast to wt-AfPA comprises only one subunit and its biosynthesis takes place directly in cytoplasm without posttranslational processing. In present work we studied thermal inactivation kinetics and temperature dependence of inactivation rate constants of wt-AfPA and pAfPA. Activation parameters values were calculated according to transition state theory. Both enzymes showed similar stability.