The specificity of biomolecular particle adhesion

Life as we know it could scarcely exist in the absence of specific interact ions between its molecular and supramolecular components. At every stage in the existence of a living organism, specificity intervenes to ensure that chance encounters are selectively guided towards further interaction. This applies to the reactions directing the development of a complex multicellul ar organism, enzyme catalysis, the immune response, etc. The efficiency of searching for specific interaction partners can be greatly increased by red ucing the dimensionality of the search space. Selectivity is enhanced by im posing a requirement for multiple binding events, within constraints of eit her time or space, in order to actuate a response. Most biological macromol ecules can exist in several stable conformational states, and switching bet ween them (conformational change) following the initial encounter between t wo biomolecules enables specificity to be further enhanced. The experimenta l determination of the parameters governing biomolecular interactions needs high resolution binding assays carried out under well defined hydrodynamic conditions. Optical waveguide lightmode spectrometry (OWLS) is well able t o fulfil these requirements. Illustrative examples using this technique are presented, demonstrating the enzymatic decomposition of polylysine, the li pid head group selectivity of actin filament polymerization and the influen ce of both head group and internal bilayer membrane structure on perforin b inding. (C) 2000 Elsevier Science B.V. All rights reserved.