Nature of the rate-determining steps of the reaction catalyzed by the Yersinia protein-tyrosine phosphatase

Zhong-Yin Zhang, William P. Malachowski, Robert L. Van Etten, Jack E. Dixon

Research output: Contribution to journalArticle

85 Citations (Scopus)

Abstract

Product inhibition and 18O exchange experiments suggest that the Yersinia protein-tyrosine phosphatase-catalyzed phosphate monoester hydrolysis proceeds through at least two different chemical steps, i.e. the formation and breakdown of a covalent phosphoenzyme intermediate. The pH dependence of k(cat) values is bell-shaped, with the apparent pK(a) derived from the acidic limb of the profile at 4.6 for both p-nitrophenyl phosphate and β-naphthyl phosphate, whereas the apparent pK(a) derived from the basic limb of the profile is substrate-dependent, with apparent pK(a) values of 5.2 and 5.8 for p-nitrophenyl phosphate and β-naphthyl phosphate, respectively. Twelve aryl phosphates with leaving groups having pK(a) values from ~7 to 10 are also examined as substrates at two pH values. At pH 4.0, the β(Ig) value is effectively zero, whereas at pH 7.5, a β(1g) value of 0.16 is observed. Collectively, our results suggest that the rate-determining step under acidic conditions corresponds to the breakdown of the phosphoenzyme intermediate, whereas under more alkaline conditions, substrate effects also contribute to the rate-limiting step. A model is proposed for the mechanism of the Yersinia protein-tyrosine phosphatase-catalyzed reaction.

Original languageEnglish (US)
Pages (from-to)8140-8145
Number of pages6
JournalJournal of Biological Chemistry
Volume269
Issue number11
StatePublished - Mar 18 1994
Externally publishedYes

Fingerprint

Yersinia
Protein Tyrosine Phosphatases
Substrates
Phosphates
Extremities
Hydrolysis
Experiments
nitrophenylphosphate
naphthyl phosphate

ASJC Scopus subject areas

  • Biochemistry

Cite this

Nature of the rate-determining steps of the reaction catalyzed by the Yersinia protein-tyrosine phosphatase. / Zhang, Zhong-Yin; Malachowski, William P.; Van Etten, Robert L.; Dixon, Jack E.

In: Journal of Biological Chemistry, Vol. 269, No. 11, 18.03.1994, p. 8140-8145.

Research output: Contribution to journalArticle

Zhang, Zhong-Yin ; Malachowski, William P. ; Van Etten, Robert L. ; Dixon, Jack E. / Nature of the rate-determining steps of the reaction catalyzed by the Yersinia protein-tyrosine phosphatase. In: Journal of Biological Chemistry. 1994 ; Vol. 269, No. 11. pp. 8140-8145.
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