Autophosphorylation kinetics of protein kinases.
Protein kinases play a central role in cellular signal transduction, by transmitting biochemical information between activated membrane-bound receptors and physiological target proteins. In addition to phosphorylating other proteins, almost all protein kinases catalyse autophosphorylation reactions (i.e. reactions in which the kinase serves as its own substrate). The autophosphorylation reactions can be intramolecular or intermolecular. In the present study, a detailed kinetic analysis of the intermolecular autophosphorylation reaction is presented. On the basis of the kinetic equations, a new procedure is developed to evaluate the kinetic parameters of the autophosphorylation reaction. This method was used to analyse the intermolecular autophosphorylation of an S6/H4 kinase from human placenta. At a fixed ATP concentration of 0.125 mM, the apparent catalytic-centre activity (turnover number; k (cat)) and apparent Michaelis-Menten constant ( K (m)) for the autophosphorylation reaction were determined to be 0.91 min(-1) and 0.86 microM respectively.
National Laboratory of Biomacromolecules, Institute of Biophysics, Academia Sinica, Beijing 100101, P.R. China. zwang@sun5.ibp.ac.cn
Zhi-Xin
ZX
Wang
Jia-Wei
JW
Wu
D000255:Adenosine Triphosphate / Q000378:metabolism; D020134:Catalytic Domain; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007700:Kinetics; D008956:Models, Chemical; D010766:Phosphorylation; D010920:Placenta / Q000201:enzymology; D011494:Protein Kinases / Q000737:chemistry* / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D017434:Protein Structure, Tertiary; D013379:Substrate Specificity; D013997:Time Factors
D000255:Adenosine Triphosphate; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases