Single-molecule active-control

It has been reported that the electrical properties of single molecules incorporating redox groups (e.g. viologens [114, 119, 120, 123, 124], oligophenylene ethynylenes [122, 123], porphyrins [111, 126], oligo-anilines and thiophenes [116, 127], metal transition complexes [118,128-132], carotenes [133], ferrocenes [134,135],perylene tetracarboxylic bisimide [93, 136, 137] and redox-active proteins [138-143]), can be switched electrochemically. Such experiments, typically performed by STM on redox-active molecules tethered via Au-S bonds between a gold substrate and a tip under potential control, allow the possibility to examine directly the correlation between redox state and the conductance of individual molecules. 

In any gas/solid catalytic system, the reactant must first be adsorbed on the catalyst surface. This is why surface characterization is so important. Studying the adsorption of various molecules under controlled conditions yields information regarding the catalyst surface area, pore volume, and pore size distribution [80]. The key factor here is accessibility. Sophisticated spectroscopic analysis of single-crystal models can tell us a lot about what goes on at the active site, but the molecules must get there first. 

Partially denatured alkaline phosphatase was assayed and compared to control enzyme. With a 15 min incubation of 8x10 M control enzyme, 9.8 3.3 peaks were observed per assay (n=4) with activities of 138 107 s . This is about twice the number observed in the single molecule assays different enzyme lots were used for the two studies. Denatured enzyme produced 4.4 1.5 peaks/assay (n=4) with an average activity of 118 97 s . At the 85% confidence limit, the means of the activities are identical and at the 75% confidence limit the standard deviations are identical. A 50% loss of the activity in bulk assay results in 45 9%... 

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