Using the rotational masking concept to enhance substrate inhibited reaction rates: controlled pore supports for enzyme immobilization

An explanation is provided on how the previously introduced concept of rotational masking^1,2 can be exploited to make the catalytic effectiveness of a substrate inhibited reaction, over an immobilized enzyme particle, greater than one. Unlike previous demonstrations of this phenomenon, no substrate concentration gradients need exist. This is advantageous since the selectivity to products in a sequential type reaction mechanism is enhanced. The practical realization of rotational masking requires that new high-technology porous supports, with stringently controlled pore sizes, need to be fabricated. Three such supports are identified: track-etched membranes, layered metal silicates and block copolymers. It is proposed that the field of immobilized enzyme catalysis has yet fully to realize, exploit and benefit from many of the remarkable catalytic phenomena that can be achieved when a highly active catalytic site is buried within accurately tailored, molecularly sized pores. The petroleum industry is already using such phenomena in molecular shape-selective zeolite catalysis.