The effect of dynamic high-pressure microfluidization on the activity, stability and conformation of trypsin

Dynamic high-pressure microfluidization (DHPM) treatment of trypsin showed no significant effects with relative activities of 98.5% (80 MPa), 98.3% (100 MPa), 97.8% (120 MPa) and 97% (160 MPa). However, DHPM treatment enhanced the pH and thermal stability of trypsin. After 100 min of incubation at 45 °C, the residual activity of trypsin treated at 80 MPa was still as high as 96% while the untreated trypsin retained only 86% of its original activity. The optimum pH of trypsin maintained surprising consistency (pH = 7.6); nevertheless, the relative activities were about 97%, 102% and 103% at 80, 100 and 120 MPa, respectively. In addition, DHPM-induced conformational changes of trypsin were observed. The unfolding of trypsin, induced by DHPM treatment, was reflected in the increase in maximum emission fluorescence intensity and exposed SH contents, as well as the decrease in total SH contents, UV absorbance and α-helix intensity.