ABSTRACT
Kinetic characteristics of model enzymes and physicochemical properties of globular proteins modified by chemical analogues of low-molecular-weight microbial autoregulators (alkylhydroxybenzenes, AHBs) have been studied. C7 and C12 AHB homologues were used, differing in the length of the alkyl radical and the capacity for weak physicochemical interactions. Both homologues affected the degree of protein swelling, viscosity, and the degree of hydrophobicity. The effects depended on the structure of AHBs, their concentration, and pH of the solution, which likely reflects changes in the charge of the protein globule and its solvate cover. Variations of hydrophobicity indices of AHB-modified enzymes (trypsin and lysozyme) were coupled to changes in the catalytic activity. The values of K(M), measured for the enzymes within both AHB complexes, did not change, whereas V(max) increased (in the case of C7 complexes) or decreased (C12 complexes). Possible molecular mechanisms of changes in the physicochemical and catalytic parameters of enzymatically active proteins, induced by modification with structurally distinct AHBs, are described, with emphasis on targeted regulation of functional activity.
Subject(s)
Gelatin/chemistry , Muramidase/chemistry , Resorcinols/chemistry , Trypsin/chemistry , Enzyme Activation , Hydrophobic and Hydrophilic Interactions , Protein Conformation , ViscosityABSTRACT
We demonstrated for the first time that alkylhydroxybenzenes (the d1 microbial autoregulatory factors involved in stress responses of cells) are capable of stabilizing enzymes in aqueous media and increasing their catalytic activity. The stabilizing effect of a chemical analogue of alkylhydroxybenzenes, C7-AHB, was established in in vitro studies with enzymes of microbial origin: a protease produced by Bacillus licheniformis, cellulase produced by Trichoderma viride, and alpha-amylase produced by Bacillus subtilis. This effect manifested itself in considerable extension of the temperature and pH ranges of the enzymatic activity. The modulation of the catalytic activities of the stabilized enzymes depended on the C7-AHB concentration and on the time of preincubation of the complexes obtained. We demonstrated that not only enzymes but also their polymeric substrates formed complexes with C7-AHB, and this also significantly influenced the efficiency of hydrolytic reactions. We also conducted comparative studies on the efficiency of hydrolytic reactions in systems in which the structure of enzymes and/or substrates was modified with C7-AHB.
