While clamped in this way, the OC-17 encourages the nanoparticles of calcium carbonate to transform into "calcite crystallites" that form the tiny of nucleus of crystals that can continue to grow on their own. But they also noticed that sometimes this chemical clamp didn't work. The OC-17 just seemed to detatch from the nanoparticle or "be desorbed".
Professor Mark Rodger from Department of Chemistry and Centre for Scientific Computing, University of Warwick, said "With the larger nanoparticles we examined we found that the binding sites for this chemical clamp were the same as the smaller nanoparticles but the binding was much weaker. In the simulations we performed, the protein never desorbed from the smaller nanoparticle, but always fell off or desorbed from the larger one. However In each case, desorption occurred at or after nucleation of calcite."
The researchers had therefore uncovered an incredibly elegant process allowing highly efficient recycling of the OC-17 protein. Effectively it acts as a catalyst, clamping on to calcium carbonate particles to kickstart crystal formation and then dropping off when the crystal nucleus is sufficiently large to grow under its own steam. This frees up the OC-17 to promote more yet more crystallisation, facilitating the speedy, literally overnight creation of an egg shell.
The researchers believe that this new insight into the elegant and highly efficient methods of promoting and controlling crystallisation in nature will be of great benefit to anyone exploring how to promote and control artificial forms of crystallisation.
|Contact: Peter Dunn|
University of Warwick