[Enzyme inactivation after exposure to mechanical factors]

Kinetics of decreasing proteolytic activity of subtilisin and trypsin during grinding of powders was studied. The enzymes were ground in a ball laboratory vibromill for 1-80 min within the temperature range 80-300 K in the air or helium. Proteolytic activity of the enzymes measured by the splitting of low molecular p-nitroanilide substrates decreases with the increase of the treatment time according to the equation of the first order. By means of titration of trypsin active centres a decrease of their number after grinding was shown. Kinetic parameters in Michaelis-Menten equation were determined for trypsin enzymic reaction. It was found that the value kappa kat decreased with an increase of the time of mechanical treatment.