Significance of reduced dimensionality in reaction kinetics: Impact of multi-site particles

This review examines novel kinetic properties of enzymes on membrane surfaces or states of restricted diffusion. A leading feature is the presence of multiple enzymes and/or substrates per particle. In these states, enzymes can be influenced by parameters such as the number of substrates or enzymes per particle, particle size, the rates of exchange of substrate or enzyme from the particle, or substrate diffusion to the particle. These steps are independent of the enzyme site parameters which are described by classical enzymology. The results make it clear that non-classical behaviors are important to biological systems, are the basis for some enzyme expression levels and are determinants of cellular design. To identify more unique functions of these states, descriptions of catalysis in the non-solution state should become a part of kinetic education in biology. Copyright (C) 1999 Elsevier Science Ireland Ltd.