In my blogs of last week and the week before, I discussed the use of evolutionary methods for improving biotechnological processes. I have also blogged, more than once, about the concept of the economy as an evolutionary ecosystem. The question then arises as to whether the development of technology in general might be seen in this way. While it is clear that minor improvements in existing products or technologies can be seen as ‘evolutionary’ advances derived from their ‘parents’ or precursors, it is not so clear how this metaphor might be applied to the arrival of novel and disruptive technologies that have no obvious precursors. That the evolutionary metaphor does work is the theme of a new book by Brian Arthur. The chief recognition is that all kinds of complex products (and these can include ‘products’ like musical symphonies!) arise largely by the combination or recombination of existing modules. These existing components may also provide novelty by processes akin to horizontal gene transfer, something that genome sequencing methods have shown us is far more common than was previously anticipated.
Now, some of these general ideas have been promoted by writers such as David Goldberg, John Koza and Stuart Kauffman, but Arthur provides a particularly readable, eloquent, coherently argued and up-to-date overview.
I tend to have a penchant for ideas and discoveries that seem to (or do) come from left field, and one that came my way this week (illustrating some of the points about novel technologies, above) was the production of the first liquid protein (or protein liquid). Now while we recognise proteins as solids, as components of colloidal aqueous (and organic) solutions, and even (inside mass spectrometers) in the gaseous phase, no one had (apparently) previously made a liquid from a pure protein (derivative) with no added solvent. Indeed, there are fundamental biophysical reasons why this is hard, since the dimensions of protein molecules typically exceed the range of their intermolecular forces, such that liquid–vapour co-existence is unattainable. To overcome this, one way would be to modify the surface properties of the protein to increase the range of the intermolecular force field to a length scale greater in size than the protein molecules, thereby enabling thermally induced molecular motions to be correlated over extended distances (i.e. to provide liquid-like behaviour).
Based in part on experiments of Giannelis and coworkers with inorganic nanostructures, this is what Mann and his colleagues at Bristol have now done, using a derivative of the iron-binding protein ferritin. It is early days yet, but the methods they use seem fairly general, albeit more favourable for spherical molecules like ferritin, and – given that there are enormous numbers of possible proteins – one can at least imagine many uses to which a protein liquid might be put. No doubt the exponents of molecular gastronomy are <ahem> licking their lips.
- Arthur WB: The nature of technology: what it is and how it evolves. London: Allen Lane, 2009
- Goldberg DE: The design of innovation: lessons from and for competent genetic algorithms. Boston: Kluwer, 2002
- Kaprelyants AS, Mukamolova GV, Kormer SS, Weichart DH, Young M, Kell DB: Intercellular signalling and the multiplication of prokaryotes: bacterial cytokines. Symp Soc Gen Microbiol 1999; 57:33-69
- Kauffman S, Lobo J, Macready WG: Optimal search on a technology landscape. J Econ Behav Organ 2000; 43:141-166
- Koza JR, Keane MA, Streeter MJ, Mydlowec W, Yu J, Lanza G: Genetic programming: routine human-competitive machine intelligence. New York: Kluwer, 2003
- Min YJ, Akbulut M, Kristiansen K, Golan Y, Israelachvili J: The role of interparticle and external forces in nanoparticle assembly. Nature Materials 2008; 7:527-538
- Perriman AW, Cölfen H, Hughes RW, Barrie CL, Mann S: Solvent-free protein liquids and liquid crystals. Angew Chem Int Ed Engl 2009; 48:6242-6246
- Salter GJ, Kell DB: Solvent selection for whole cell biotransformations in organic media. CRC Crit Rev Biotechnol 1995; 15:139-177
- Warren SC, Banholzer MJ, Slaughter LS, Giannelis EP, DiSalvo FJ, Wiesner UB: Generalized route to metal nanoparticles with liquid behavior. J Am Chem Soc 2006; 128:12074-12075
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