Generating favorable nano‐environments for thermal and solvent stabilization of immobilized β‐galactosidase

β‐Galactosidase ( Escherichia coli ) was immobilized through its thiol groups on thiolsulfinate‐agarose gel. After enzyme immobilization, different nano‐environments were generated by reacting the excess of gel‐bound thiolsulfinate moieties with 2‐mercaptoethanesulfonic acid (S‐gel), glutathione (G‐gel), cysteamine (C‐gel), and mercaptoethanol (M‐gel). Concerning thermal stability at 50°C, the G‐gel and the M‐gel derivatives were the most stable with residual activity values of 67% and 45%, respectively. The stability in several solvent systems was studied: ethyl acetate (1.6% vol/vol), ethylene glycol (50% vol/vol), and 2‐propanol (50% vol/vol). In ethyl acetate, both the M‐gel and S‐gel were highly stabilized; the time required for activity to decay to 80% of the initial activity was increased 29‐fold for the M‐gel and 20‐fold for the S‐gel with respect to the soluble enzyme. The G‐gel was the least stable of all the derivatives. The different behaviors of the derivatives in thermal and solvent stability studies suggest that each nano‐environment contributes differently to the enzyme stability, depending on the denaturing conditions. Therefore, it may be possible to tailor the matrix surface to maximize enzyme stability in particular applications. © 2002 John Wiley & Sons, Inc. Biotechnol Bioeng 77: 430–434, 2002; DOI 10.1002/bit.10109