This paper is dedicated to William P. Jencks, a great scientist and an inspiration to generations of chemists past, present and future.
Article first published online: 25 MAY 2004
Copyright © 2004 John Wiley & Sons, Ltd.
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
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
Selected paper part of a special issue entitled ‘Biological Applications of Physical Organic Chemistry’.
- Issue published online: 25 MAY 2004
- Article first published online: 25 MAY 2004
- Manuscript Revised: 9 OCT 2003
- Manuscript Accepted: 9 OCT 2003
- Manuscript Received: 29 JUL 2003
- National Institutes of Health. Grant Number: GM47297
- Petroleum Research Fund. Grant Number: 35690-AC4
- Utah State University
- sulfuryl transfer;
- catalytic mechanism;
- isotope effect
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 SO 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.