FEBS Letters
Volume 584, Issue 13 , Pages 2759-2766, 2 July 2010

Examining the case for the effect of barrier compression on tunneling, vibrationally enhanced catalysis, catalytic entropy and related issues

Edited by Peter Brzezinski

  • Shina Caroline Lynn Kamerlin

      Affiliations

    • Department of Chemistry (SGM418), University of Southern California, 3620 McClintock Ave., Los Angeles, CA 90089, USA
    • ,
  • Janez Mavri

      Affiliations

    • National Institute of Chemistry, Hajdrihova 19, P.O. Box 660, SI-1001 Ljubljana, Slovenia
    • ,
  • A. Warshel

      Affiliations

    • Department of Chemistry (SGM418), University of Southern California, 3620 McClintock Ave., Los Angeles, CA 90089, USA
    • Corresponding Author InformationCorresponding author. Fax: +1 213 740 2701.

Received 7 April 2010; received in revised form 21 April 2010; accepted 22 April 2010. published online 28 April 2010.

Abstract 

The idea that tunneling is enhanced by the compression of the donor–acceptor distance has attracted significant interest. In particular, recent studies argued that this proposal is consistent with pressure effects on enzymatic reactions, and that the observed pressure effects support the idea of vibrationally enhanced catalysis. However, a careful analysis of the current works reveals serious inconsistencies in the evidence presented to support these hypotheses. Apparently, tunneling decreases upon compression, and external pressure does not lead to the applicable compression of the free energy surface. Additionally, pressure experiments do not provide actual evidence for vibrationally enhanced catalysis. Finally, the temperature dependence of the entropy change in hydride transfer reactions is shown to reflect simple electrostatic effects.

Keywords: Enzyme catalysis, Tunneling, Barrier compression, Promoting mode, Kinetic isotope effect, Catalytic entropy

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PII: S0014-5793(10)00347-9

doi:10.1016/j.febslet.2010.04.062

FEBS Letters
Volume 584, Issue 13 , Pages 2759-2766, 2 July 2010

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