Assessment of the Effects of Attaching an Enzyme to Glass by a Poly(ethylene glycol) Tether

Abstract

Modification of surfaces and proteins by attaching poly(ethylene glycol) (PEG) is an important technique for controlling the properties of these materials. Our goal is to examine the possible combination of these effects by linking proteins to surfaces via a PEG spacer or tether. In the present work we have coupled alkaline phosphatase (as a model protein) to porous glass by means of PEG spacers, and we have compared the activity and operational sta bility of the PEG-bound enzyme to free enzyme and to enzyme immobilized by a conventional, short urea linkage. Significantly, the PEG-bound enzyme differs little in its catalytic properties from free enzyme, indicating that the bound enzyme extends into solution and is in essence free of the surface.