Studies on the adsorption of glucoamylase on molecular sieves

The adsorption isotherms of glucoamylase (E.C.3.2.1.3) on modified molecula r sieves DY with mesopore and macropore were determined. The enzyme adsorpt ion amount and the shapes of the isotherm were related to the properties su ch as point of zero charge(PZC), pore volume, pore diameter and acidity of the molecular sieves DY and the pH of the adsorbing solution. The relations hip among acidity, pore structure of molecular sieves, adsorption amount of enzyme and activity of the enzyme adsorbed was also discussed. The results show that the adsorption amount is closely related to the procedure that a pplied to modify the molecular sieve, which makes the molecular sieves DY w ith different Si/Al ratio, pore distribution and specific surface area. Thu s, the different Si/Al ratio causes the molecular sieves DY to have differe nt acidity properties and different PZC. It is found that the main drive fo rce for glucoamylase adsorbing on molecular sieves is electrostatic interac tion. The experimental results also show that for the molecular sieves DY t he enzyme adsorption amount increases with the increase of the surface acid ity, the pore diameter and pore volume, and the enzyme activity increases w ith the increase of enzyme adsorption amount while the specific activity de creases with the increase of enzyme adsorption amount and the decrease of m esopore diameter and volume of the molecular sieves DY.