Penicillin V acylase (PVA) (penicillin amidohydrolase, EC 3.5.1.11) from Streptomyces lavendulae is an extracellular enzyme with interesting properties for the industrial production of 6-aminopenicillanic acid (6-APA), the nucleus of a large number of semisynthetic penicillins with important therapeutic advantages [1, 2]. The enzyme hydrolysed penicillin V and other natural aliphatic penicillins (penicillin F, penicillin dihydroF and penicillin K) to yield 6-APA and the corresponding carboxylic acid.

Since certain detergents are able to increase the activity and/or stability of enzymes [3], we have studied the effects of several surfactants on PVA activity with penicillin V as substrate.

Different behaviours were observed. Non-ionic detergents Nonidet P-40 and Triton X-100, and the zwitterionic deoxycholate increased the activity 3 and 4-fold respectively, at surfactant concentrations higher than their critical micellar concentration (CMC). In these conditions there was an increase of catalytic efficiency (Vmax/K_M), due to an increase in Vmax, since K_M did not change significantly. This apparent activation may be due to the ability of these detergents to stabilise proteins [4].

By contrast, non-ionic detergents such as Tween 20, lubrol and octylglucoside decreased drastically the activity at surfactant concentration lower than their CMC. The monomers of these detergents have lateral aliphatic chains suitable to interact with the active site of PVA as competitive inhibitors.

[1] Hamilton-Miller, J.M.T., Bacteriol. Rev., 30, 761-782, 1996.

[2] Huber, F.M., Chauvette, R.R. and Jackson, B.G., in Cephalosporins and Penicillins Compounds: Their Chemistry and Biology, (Flynn, E.H:; Ed), Academic Press, New York, 27-73, 1973.

[3] Viparelli, P., Alfani, F. and Cantarella, M., Biochem. J., 344, 765-773, 1999.

[4] Komori, Y. Chiang, K.T. and Fukuto, J.M., Archv. Biochem. Biophys., 307, 311-315, 1993.