Kinetic analysis of a protein tyrosine kinase reaction transition state in the forward and reverse directions

Kyonghee Kim, Philip A. Cole

Research output: Contribution to journalArticle

Abstract

Protein tyrosine kinases catalyze the transfer of the γ-phosphoryl group from ATP to tyrosine residues in proteins and are important enzymes in cell signal transduction. We have investigated the catalytic phosphoryl transfer transition state of a protein tyrosine kinase reaction catalyzed by Csk by analyzing a series of fluorotyrosine-containing peptide substrates. It was established for five such fluorotyrosine-containing peptide substrates that there is good agreement between the tyrosine analogue phenol pK(a) and the ionizable group responsible for the basic limb of a pH rate profile analysis. This indicates that the substrate tyrosine phenol must be neutral to be enzymatically active. Taken together with previous data indicating a small β(nucleophile) coefficient (0-0.1), these results strongly support a dissociative transition state for phosphoryl transfer. In addition, the β(leaving group) coefficient was measured for the reverse protein tyrosine kinase reaction and shown to be -0.3. This value is in good agreement with a previously reported nonenzymatic model phosphoryl transfer reaction carried out under acidic conditions (pH 4) and is most readily explained by a transition state with significant proton transfer to the departing phenol.

Original languageEnglish (US)
Pages (from-to)6851-6858
Number of pages8
JournalJournal of the American Chemical Society
Volume120
Issue number28
DOIs
StatePublished - Jul 22 1998
Externally publishedYes

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Phenol
Protein-Tyrosine Kinases
Tyrosine
Phenols
Proteins
Kinetics
Substrates
Peptides
Signal transduction
Nucleophiles
Proton transfer
Protons
Adenosinetriphosphate
Signal Transduction
Extremities
Adenosine Triphosphate
Enzymes
Direction compound

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

Kinetic analysis of a protein tyrosine kinase reaction transition state in the forward and reverse directions. / Kim, Kyonghee; Cole, Philip A.

In: Journal of the American Chemical Society, Vol. 120, No. 28, 22.07.1998, p. 6851-6858.

Research output: Contribution to journalArticle

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