The influence of Zn(II) and Mn(II) on catalytic activity of C. albicans aspartic proteinases

The interaction of secreted aspartic proteinases from C. albicans (C. albicans SAP) with ZnCl2 and MnCl2 has been studied. Logarithms of stability constant from the data of electronic spectroscopy were calculated for the complexes of SAP with Zn (II) (SAP-ZnII, logβ = 4.73 ± 0.20) and with Mn(II) (SAP-MnII, logβ = 7.02 ± 0.20). The composition and maximum accumulation of complexes in solution were calculated. The optimal conditions of hydrolysis of the substrate, HAS (human serum albumin) in the presence of C. albicans SAP-MnII and SAP-ZnII proteinases were determined. These were: [HSA] = 1 mg/ml, [SAP] = 2.33 μM, pH = 4.5, incubation time of 25 min. The activity of C. albicans SAP in the presence of different concentrations of ZnCl₂ and MnCl₂ was evaluated under optimal conditions of enzymatic hydrolysis. For the first time the activating action of 0.5 μM ZnCl₂ on catalytic activity of C. albicans SAP proteinase has been demonstrated. The maximal rate of enzymatic reaction (V _max), the Michaelis constant (K _m ) and constants of effects in the presence and in the absence of the effector, ZnCl₂, were calculated. The albuminase activity of C. albicans pathogenic strains of different localization was evaluated in the presence and the absence of the effector of ZnCl₂.