[Atomic force microscopy visualization and measurement of the activity and physicochemical properties of single...

An approach to measure the activity of single oligomers of the heme-containing enzyme the cytochrome P450 CYP102A1 (CYP102A1) by atomic force microscopy (AFM) has been developed. It was found that the amplitude of fluctuations of the height of single CYP102A1 molecules performing the catalytic cycle is twice as great as the amplitude of fluctuations of the height of the same enzymes in the inactive state. It was shown that the amplitude of height fluctuations of a CYP102A1 protein globule depends on temperature, the maximum of this dependence being observed at 22 degrees C. The activity of a single CYP102A1 molecule in the unit amplitude of height fluctuations of a protein globule reduced to the unit time was 5+/-2 Ac. The elasticity of a single protein molecule was measured from the deformation of this molecule by the action of an AFM probe. The use of AFM probes of different geometry made i t possible t o determine t he integral andlocal Young's modulus for the monomers of the protein putidaredoxin reductase from the cytochrome P450 CYP101 (P450cam)-containing monooxigenase system, which were 37+/-117 and 1+/-3 MPa, respectively.