Changing enzyme kinetic parameters of chymotrypsin and NAD-dependent formate dehydrogenase under low-frequency magnetic field

Nanomechanical approach for biochemical reaction management means that, rotation of magnetic nanoparticles (MNPs) with immobilized on them enzyme under expose of alternative magnetic field is applied for changing an enzyme... [ view full abstract ]

Nanomechanical approach for biochemical reaction management means that, rotation of magnetic nanoparticles (MNPs) with immobilized on them enzyme under expose of alternative magnetic field is applied for changing an enzyme structure-activity [1, 2] (fig. 1). When enzyme immobilized between two MNPs, rotation of MNP under low-frequency magnetic field (LFMF) can significantly change the enzyme structure leading to the decrease of the enzyme activity. In case of enzyme molecules immobilized on single MNP, the hydrodynamic forces changing the enzyme structure more mild. In this work we demonstratethe effect of LFMF on activity of different enzymes, immobilized on single-domain magnetite@gold nanoparticles.

Previously we have shown [1] that enzymatic activity of chymotrypsin, immobilized on the aggregates of magnetite nanoparticles, decrease under impact of LFMF. To determine the mechanism of such inactivation we carried out a molecular modeling experiment where we applied stretch forces to chymotrypsin molecule. As a result of modeling we have found that enzyme catalytic center had no difference from the initial structure while the binding site has becomein more closed state. As a result of LFMF expose to immobilized on dimeric magnetite@gold nanoparticles chymotrypsin, we observed an increase in K_m value while V_m remained unchanged (fig 2). Thus, experimental data of kinetic parameters measurements confirmed our data on molecular modeling.

Another example of nanomechanical “devices” that could change structure-activity properties of enzyme is a single magnetic nanoparticle with enzyme, immobilized on its surface. Here, we demonstrate changing enzymatic parameters of immobilized on a single magnetite@gold nanoparticle NAD-dependent formatedehydrogenase after expose to LFMF (Table 1).

Figure 1.Different forces and deformations that appearin enzyme macromolecule, immobilized on single-domain MNP, as a result of Brownian relaxation under expose of LFMF.

Figure 2.Impact of low-frequency magnetic field(50 Hz, 0.14 T) on enzymatic rate of chymotrypsin immobilized on aggregates of magnetite@gold nanoparticles

Table 1. Changing enzymatic parameters of NAD-dependentformate dehydrogenase immobilized on magnetite@gold nanoparticles after expose to 77 Hz and 0.1 T magnetic field for 5 min