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J Am Chem Soc. 2015 Oct 14;137(40):12740-3. doi: 10.1021/jacs.5b06211. Epub 2015 Sep 30.

Amplified Rate Acceleration by Simultaneous Up-Regulation of Multiple Active Sites in an Endo-Functionalized Porous Capsule.

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Department of Chemistry, Ben Gurion University of the Negev , Beer Sheva 84105, Israel.
Faculty of Chemistry, University of Bielefeld , Bielefeld D-33501, Germany.


Using the hydrolysis of epoxides in water as a model reaction, the effect of multiple active sites on Michaelis-Menten compliant rate accelerations in a porous capsule is demonstrated. The capsule is a water-soluble Ih-symmetry Keplerate-type complex of the form, [{Mo(VI)6O21(H2O)6}12{Mo(V)2O4(L)}30](42-), in which 12 pentagonal "ligands," {(Mo(VI))Mo(VI)5O21(H2O)6}(6-), are coordinated to 30 dimolybdenum sites, {Mo(V)2O4L}(1+) (L = an endohedrally coordinated η(2)-bound carboxylate anion), resulting in 20 Mo9O9 pores. When "up-regulated" by removal of ca. one-third of the blocking ligands, L, an equal number of dimolybdenum sites are activated, and the newly freed-up space allows for encapsulation of nearly twice as many substrate guests, leading to a larger effective molarity (amplification), and an increase in the rate acceleration (k(cat)/k(uncat)) from 16,000 to an enzyme-like value of 182,800.

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