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. 1971 Aug;68(8):1678–1683. doi: 10.1073/pnas.68.8.1678

Entropic Contributions to Rate Accelerations in Enzymic and Intramolecular Reactions and the Chelate Effect

Michael I Page 1, William P Jencks 1,*
PMCID: PMC389269  PMID: 5288752

Abstract

It is pointed out that translational and (overall) rotational motions provide the important entropic driving force for enzymic and intramolecular rate accelerations and the chelate effect; internal rotations and unusually severe orientational requirements are generally of secondary importance. The loss of translational and (overall) rotational entropy for 2 → 1 reactions in solution is ordinarily on the order of 45 entropy units (e.u.) (standard state 1 M, 25°C); the translational entropy is much larger than 8 e.u. (corresponding to 55 M). Low-frequency motions in products and transition states, about 17 e.u. for cyclopentadiene dimerization, partially compensate for this loss, but “effective concentrations” on the order of 108 M may be accounted for without the introduction of new chemical concepts or terms.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Bruice T. C., Brown A., Harris D. O. On the concept of orbital steering in catalytic reactions. Proc Natl Acad Sci U S A. 1971 Mar;68(3):658–661. doi: 10.1073/pnas.68.3.658. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Bruice T. C., Brown A., Harris D. O. On the concept of orbital steering in catalytic reactions. Proc Natl Acad Sci U S A. 1971 Mar;68(3):658–661. doi: 10.1073/pnas.68.3.658. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Jencks W. P., Barley F., Barnett R., Gilchrist M. The free energy of hydrolysis of acetic anhydride. J Am Chem Soc. 1966 Oct 5;88(19):4464–4467. doi: 10.1021/ja00971a030. [DOI] [PubMed] [Google Scholar]
  4. Jencks W. P., Barley F., Barnett R., Gilchrist M. The free energy of hydrolysis of acetic anhydride. J Am Chem Soc. 1966 Oct 5;88(19):4464–4467. doi: 10.1021/ja00971a030. [DOI] [PubMed] [Google Scholar]
  5. Milstien S., Cohen L. A. Rate acceleration by stereopopulation control: models for enzyme action. Proc Natl Acad Sci U S A. 1970 Nov;67(3):1143–1147. doi: 10.1073/pnas.67.3.1143. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Milstien S., Cohen L. A. Rate acceleration by stereopopulation control: models for enzyme action. Proc Natl Acad Sci U S A. 1970 Nov;67(3):1143–1147. doi: 10.1073/pnas.67.3.1143. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Storm D. R., Koshland D. E. A source for the special catalytic power of enzymes: orbital steering. Proc Natl Acad Sci U S A. 1970 Jun;66(2):445–452. doi: 10.1073/pnas.66.2.445. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Storm D. R., Koshland D. E. A source for the special catalytic power of enzymes: orbital steering. Proc Natl Acad Sci U S A. 1970 Jun;66(2):445–452. doi: 10.1073/pnas.66.2.445. [DOI] [PMC free article] [PubMed] [Google Scholar]

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