Laissez-faire Versus Keynesian

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Science  07 Feb 2003:
Vol. 299, Issue 5608, pp. 785
DOI: 10.1126/science.299.5608.785a

How enzymes lower the activation energy of reactions has almost as many answers as there are enzyme structures. Hur and Bruice use molecular dynamics simulations to compare and contrast a pair of intramolecular rearrangements: chalcone to (S)-flavanone and chorismate to prephenate. Both enzymes (chalcone isomerase and chorismate mutase) achieve comparable rate enhancements, decreasing the energy barrier from about 25 kcal/mol for the aqueous reaction to about 15 kcal/mol. However, the former relies on actively abetting nucleophilic attack by an enolate, whereas the latter merely watches after capturing the rare chorismate conformer in which the Claisen rearrangement is already primed and ready to go. — GJC

J. Am. Chem. Soc. 10.1021/ja0293047 (2003).

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