A joint lecture with the Institute of Biology.
Why might a theoretical physicist work with the life sciences? What do electrons, quarks, black holes and lasers to do with cell walls, nano-membranes and the genome? Tom McLeish is convinced that physics has a central rôle to play in this multidisciplinary project.
The last 30 years have seen the resurgence of physicists’ interest in a general field now called “soft condensed matter”. This nano-scale domain of giant molecules, membranes, de-mixing and self-structuring fluids, is dominated by the continuous random “Brownian Motion” that is the molecular manifestation of heat. Brownian motion has counterintuitive properties: it endows elasticity to labile structures and arbitrates between alternative ways of assembling molecular components. Working with it, rather than against it, is a fundamental rule of nanotechnology. The search problem of “protein folding” is one example of problem-solving in a stochastic world.
We examine one example of a recent theme in which theoretical physics has shed light and help direct a programme investigating the self-assembly of “nanofibrils” from peptide molecules, small versions of proteins. The aggregation of these molecules forms a hierarchy of structures that closely resembles “amyloid” fibrils in the brain tissue of patients suffering from Alzheimer’s disease. Surprisingly, the nature of the structures is clarified by a physical theory that relates them to a very small set of energies. We speculate that when physics meets biology it may have more to say when things go wrong than when they behave accordingly to highly evolved biological norms!