Research Article

Investigation of the sulfuryl transfer step from substrate to enzyme by arylsulfatases†‡

  1. Stuart G. Gibby,
  2. Jarod M. Younker,
  3. Alvan C. Hengge*

Article first published online: 25 MAY 2004

DOI: 10.1002/poc.775

Issue

Journal of Physical Organic Chemistry

Journal of Physical Organic Chemistry

Special Issue: Biological Applications of Physical Organic Chemistry dedicated to Prof. William P. Jencks

Volume 17, Issue 6-7, pages 541–547, June - July 2004

Additional Information

How to Cite

Gibby, S. G., Younker, J. M. and Hengge, A. C. (2004), Investigation of the sulfuryl transfer step from substrate to enzyme by arylsulfatases. J. Phys. Org. Chem., 17: 541–547. doi: 10.1002/poc.775

Author Information

  1. Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322, USA

*Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322, USA.

  1. †

    This paper is dedicated to William P. Jencks, a great scientist and an inspiration to generations of chemists past, present and future.

  2. ‡

    Selected paper part of a special issue entitled ‘Biological Applications of Physical Organic Chemistry’.

Publication History

  1. Issue published online: 25 MAY 2004
  2. Article first published online: 25 MAY 2004
  3. Manuscript Revised: 9 OCT 2003
  4. Manuscript Accepted: 9 OCT 2003
  5. Manuscript Received: 29 JUL 2003

Funded by

  • National Institutes of Health. Grant Number: GM47297
  • Petroleum Research Fund. Grant Number: 35690-AC4
  • Utah State University

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Keywords:

  • arylsulfatase;
  • sulfuryl transfer;
  • catalytic mechanism;
  • isotope effect

Abstract

The reactions of the arylsulfatase A (ASA) from Helix pomatia and that from Aerobacter aerogenes with p-nitrophenyl sulfate were examined by determination of the pH dependence of Vmax/Km and by measurement of kinetic isotope effects. Both enzymes exhibit bell-shaped pH–rate dependences for Vmax/Km. The ASA from Helix pomatia exhibits a more acidic pH optimum (pH 4–5) than the ASA from Aerobacter aerogenes (pH ∼7). The sulfuryl transfer from substrate to enzyme is general acid-assisted in both enzymes, but isotope effects indicate differences in the synchronicity of protonation with S[BOND]O bond fission. In the reaction of the Helix pomatia enzyme, protonation is synchronous with bond fission and the leaving group is fully neutralized in the transition state. In the reaction catalyzed by the Aerobacter aerogenes ASA, protonation of the leaving group lags behind bond fission and the leaving group bears a partial negative charge in the transition state. Copyright © 2004 John Wiley & Sons, Ltd.

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