Studies on the Modification of Maltose and the Chemical Modification of Trypsin with Maltose

Objective:Trypsin was modified with maltose by oxidation method with sodium periodate.Whether this method could improve the stability of trypsin was checked.Method:Maltose was modified with sodium periodate,in order that there was aldehyde group which could combine with amino-group of enzyme molecule in it,so it could modify trypsin chemically under certain conditions.Result:The optimum conditions for modifying maltose were as follows:Concentration of sodium periodate 0.05g/mL,Mass ratio of sodium periodate and maltose 1.1∶1,Initial pH 1.0,Reaction time 3h,Reaction temperature 30℃;The optimum conditions for modifying trypsin were as follows:pH 6.0,Mass ratio of modified maltose and trypsin 1∶1,Modification temperature 4℃,Modification time 24h;After trypsin was modified under the optimum conditions,the activity of the original trypsin and the modified trypsin dropped 15.8% and 9.8% of their highest activity respectively within pH8.9-10.0;Under 50℃ for 2h,the activity of the original trypsin and the modified trypsin retained 88.7% and 94.7% of their activity under 4℃ for 2h respectively.Conclusion:This method could improve stability for resisting alkali and heat of trypsin.