COLL 45 |
| Ilya Reviakine and Peter Vekilov. Department of Chemical Engineering, University of Houston, Houston, TX 77204 |
| The rombohedral form of the three-dimensional insulin crystals was investigated by tapping mode (TM) and contact mode atomic force microscopy (AFM) in mother liquor. TM-AFM was used to follow, in situ and in real time, the growth and dissolution of the crystals at various supersaturations. It was found that growth proceeded by the generation of steps at screw dislocations. Propagation of individual steps was followed at near-lattice resolution. Step velocity and step density were measured. It was concluded from those measurements that steps did not interact with each other. Contact mode AFM was used to record sub-molecular (11Å) resolution images of the <100> face of the crystal. Insulin hexamers were clearly visible on the unprocessed images. Features evident on their surfaces after processing by standard Fourier methods could be correlated with those expected from the model calculated from the X-ray diffraction studies of this crystal form. |
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Nanoscale Imaging of Biological Systems
Division of Colloid and Surface Chemistry |