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 language | English (US) |
|---|---|
| Pages (from-to) | 6851-6858 |
| Number of pages | 8 |
| Journal | Journal of the American Chemical Society |
| Volume | 120 |
| Issue number | 28 |
| DOIs | |
| State | Published - Jul 22 1998 |
| Externally published | Yes |
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ASJC Scopus subject areas
- Chemistry(all)
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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 journal › Article
}
TY - JOUR
T1 - Kinetic analysis of a protein tyrosine kinase reaction transition state in the forward and reverse directions
AU - Kim, Kyonghee
AU - Cole, Philip A.
PY - 1998/7/22
Y1 - 1998/7/22
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=0032558125&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0032558125&partnerID=8YFLogxK
U2 - 10.1021/ja9808393
DO - 10.1021/ja9808393
M3 - Article
AN - SCOPUS:0032558125
VL - 120
SP - 6851
EP - 6858
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 28
ER -