Enhanced enzymatic activity and stability of trypsin by reductive alkylation in solid phase

Amino groups of trypsin (EC 3.4.21.4) were reductively alkylated in solid phase to obtain a surface-active and biologically active enzyme in an o/w emulsion system. Trypsin adsorbed on a benzamidine-sepharose column was reductively alkylated with n-octanal in the presence of sodium borohydride, i.e., trypsin-C8. Activity of trypsin-C8 against Nalpha-benzoyl-L-arginine-p-nitroanilide was three times higher than that of native trypsin. Activities of trypsin and trypsin-C8 against casein were almost the same. After incubating the trypsin solution at 40 degrees C for 1 h, residual activities in the emulsion and solution systems were 64.2 and 57.4%, respectively. On the other hand, residual activities of native trypsin following incubation were 21.8% in the emulsion system and 33.2% in the solution system. Enhancement of trypsin-C8 stability in the emulsion system may derive from interaction between the hydrophobic areas of trypsin-C8 molecules and the hydrophobic phase of the emulsion.