An interesting pair of articles showed up this week, both from Chad Mirkin's lab at the Nanotechnology Center of Northwestern University. You can find them both in the August 22 edition of JACS. The essence of these articles is that Mirkin's group has created a group of macrocyclic catalysts that can be allosterically regulated by small ligands. The basic principle is shown below (figure taken from the second paper):
The catalytic molecule has a small intrinsic ability to catalyze the chemical conversion of the small molecules, as shown on the left. The addition of the "Analytes" in this case Cl- and CO, displaces the sulfur coordinating groups that are weakly bound to the rhodium or copper metal centers. Removing the sulfur coordination allows the molecule to undergo a conformational change, opening up to adopt a new structure that is vastly more effective as a catalyst. This mimics the allosteric regulation of protein catalysts and binding proteins by ligands.
The approach is a pretty clever bit of molecular engineering, and an important step forward for nanotechnology. Though it remains to be seen how well these molecules survive under field conditions (reducing/oxidizing environments, complex solutions), they have a feature that will be absolutely essential for functional nanomachines, namely that they can be regulated. The ability to turn our microscopic tools on and off will be an important part of producing useful nanomachines, to say nothing of avoiding the "gray goo" of sci-fi nightmares.
If you're interested, check out these articles:
Kuwabara, J. Stern, C.L., and Mirkin, C.A. "A Coordination Chemistry Approach to a Multieffector Enzyme Mimic", J. Am. Chem. Soc. 129 (2007) p. 10074-10075.
Masar III, M.S., Gianneschi, N.C., Oliveri, C.G., Stern, C.L., Nguyen, S.T., and Mirkin, C.A. "Allosterically Regulated Supramolecular Catalysis of Acyl Transfer Reactions for Signal Amplification and Detection of Small Molecules" J. Am. Chem. Soc. 129 (2007) p. 10149-10158.
I recommend the first article for lay readers, and the second for the hardcore.
The catalytic molecule has a small intrinsic ability to catalyze the chemical conversion of the small molecules, as shown on the left. The addition of the "Analytes" in this case Cl- and CO, displaces the sulfur coordinating groups that are weakly bound to the rhodium or copper metal centers. Removing the sulfur coordination allows the molecule to undergo a conformational change, opening up to adopt a new structure that is vastly more effective as a catalyst. This mimics the allosteric regulation of protein catalysts and binding proteins by ligands.The approach is a pretty clever bit of molecular engineering, and an important step forward for nanotechnology. Though it remains to be seen how well these molecules survive under field conditions (reducing/oxidizing environments, complex solutions), they have a feature that will be absolutely essential for functional nanomachines, namely that they can be regulated. The ability to turn our microscopic tools on and off will be an important part of producing useful nanomachines, to say nothing of avoiding the "gray goo" of sci-fi nightmares.
If you're interested, check out these articles:
Kuwabara, J. Stern, C.L., and Mirkin, C.A. "A Coordination Chemistry Approach to a Multieffector Enzyme Mimic", J. Am. Chem. Soc. 129 (2007) p. 10074-10075.
Masar III, M.S., Gianneschi, N.C., Oliveri, C.G., Stern, C.L., Nguyen, S.T., and Mirkin, C.A. "Allosterically Regulated Supramolecular Catalysis of Acyl Transfer Reactions for Signal Amplification and Detection of Small Molecules" J. Am. Chem. Soc. 129 (2007) p. 10149-10158.
I recommend the first article for lay readers, and the second for the hardcore.
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