Biology of the inner space: voids in biopolymers

Dynamic states of biopolymers are associated with appearance and disappearance of spaces, or voids, to an extent larger than what is hitherto recognized. Current awareness of the existence of free space in biopolymers is by and large restricted in terms of (i) essentially small pores obeying Boltzman distribution of sizes and energy and (ii) rigid structures dictated by structural constraints, whose volume merely exhibits fluctuations within the thermal limits. Interconnectivity of these spaces within biopolymers such as membranes give rises to new possibilities in addressing some of the long standing problems in understanding catalysis, transport and the derived biological phenomena. Given the a priori recognition that other kinds of space can exist in biopolymers, which are dynamic, predominantly inducible and possibly larger, a new kind of experimentation becomes possible as also a new set of constraints for the acceptability of molecular models of interactions in the explanation of biological phenomena. The theory of adsorption of liquids and presence of structural cavities as exemplified by zeolites competently accounts for much of the current thinking in our understanding of cavities in biopolymers. Induction of (larger) voids requires approaches that are significantly different. We suggest that it is necessary to consider a reservoir of inner space as a specific contribution to the energetics of polymer dynamics. We outline a methodological approach that helps identify these voids as well as biological phenomena in which the notion of dynamics of voids would bring novel insights. Copyright 1998 Academic Press