Figure 1.
Outline of the experimental system.
Lipase and chitinase molecules are immobilized on superparamagnetic particles, the average diameter and magnetic dipole moment of which are 130 nm and 3.31×10−23 Wb m, by mixing the particles with aqueous solution, in which lipase and chitinase molecules are dispersed. Dc and rotational magnetic fields are generated by modulating the phase of the electric current supplied to each pair of electromagnets using a function generator. The strength of the magnetic field is set at 9.55 kA m−1, which corresponds to a magnetic flux density of 12 mT, and the frequency of the magnetic field is changed; 1, 3, 5, 7, 10 and 30 Hz. The enzyme-substrate reaction experiment is carried out at 25°C for 30 minutes and the enzyme activity is estimated by measuring the absorbance of 410 nm photons.
Figure 2.
Dependence of the relative activities on the frequency of the external rotational magnetic field.
(a) Lipase. (b) Chitinase. The ordinate axis represents the activity of the enzymes immobilized on particles in a rotational magnetic field, which is normalized by that in the absence of a magnetic field. The diameter of each particle is 130 nm. The strength of the magnetic field is 9.55 kA m−1. The activities increase and become maximum at certain frequencies.