Hexokinase
The enzyme hexokinase phosphorylates (adds a phosphate group to) glucose in the cell's cytoplasm. In the process, a phosphate group from Adenosine triphosphate (ATP) is transferred to glucose producing glucose 6-phosphate (Glc6P).
Contents
Chemical equation
Rate equation
Without inhibition
Random Bi-Bi Michaelis Menten is used.[1]
With allosteric inhibition
Hexokinase is allosterically inhibited by Glc6P [2]. The rate law taking into account this inhibition is
Parameters
Without inhibition
Parameter | Value | Units | Organism | Remarks |
---|---|---|---|---|
0.04 [3] | HeLa cell line | |||
651[4] | ||||
0.1[1] | mM | |||
1.1[1] | mM | |||
[1] | mM | |||
3.5[1] | mM |
With inhibition
Parameter | Value | Units | Organism | Remarks |
---|---|---|---|---|
0.04 [3] | HeLa cell line | |||
0.1[1] | mM | |||
1.1[1] | mM | |||
[2] | mM |
Parameters with uncertainty
Hexokinase isoenzyme has been reported to vary in different developmental and metabolic status of the cell. In mammalian tissues four isoenzymes of Hexokinase is present [5]. Hexokinase-II has been found to be overexpressed in several first growith cancer cells [3]. Therefore in our model we have considered only the Hexokinase-II kinetic parameter values.
Parameter | Value | Units | Organism | Remarks |
---|---|---|---|---|
Failed to parse (Cannot store math image on filesystem.): 0.02 \pm 0.006 (n=4)[3] | HeLA cell line | |||
(n=5)[6] | mM | SNU449 cell (Human Liver Tissue) | ||
(n=5)[6] | mM | |||
(n=5)[6] | mM |
Equilibrium constant
Equilibrium constant | Conditions | Source |
---|---|---|
4908 | pH=7, T=25°C | Voet et al.[7] from Newshole et al. (1973) [8]: , |
846 | pH=7, T=25°C | Lehninger, (1975)[9] p 553: , |
890 | pH=7, T=25°C | Lehninger, (1975)[10] p 396 |
Calculating average from these equlibrium constant gives the value of
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Marín-Hernández A, Gallardo-Pérez JC, Rodríguez-Enríquez S et al (2011) Modeling cancer glycolysis. Biochim Biophys Acta 1807:755–767 (doi)
- ↑ 2.0 2.1 Wilson J E (2003). Isozymes of mammalian hexokinase: structure, subcellular localization and metabolic function. Journal of Experimental Biology, 206, pp. 2049–2057 (doi)
- ↑ 3.0 3.1 3.2 3.3 Marín-Hernández A , Rodríguez-Enríquez S, Vital-González P A, et al. (2006). Determining and understanding the control of glycolysis in fast-growth tumor cells. Flux control by an over-expressed but strongly product-inhibited hexokinase. FEBS J., 273 , pp. 1975–1988(doi) Cite error: Invalid
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- ↑ Adams V, Kempf W, Hassam S, Briner J. (1995), Determination of hexokinase isoenzyme I and II by RT-PCR: increased hexokinase II isoenzyme in human renal cell carcinoma. J Biochem Mol Med 1995;54:53–58.
- ↑ 6.0 6.1 6.2 Ahn, K.J.; Kim, J.; Yun, M.; Park, J.H.; Lee, J.D.(2009), Enzymatic properties of the N- and C-terminal halves of human hexokinase II, BMB Rep. 42, 350-355.
- ↑ Voet, D., Voet., J.G. and Pratt, C. W. (1999) Fundamentals of biochemistry, Wiley
- ↑ Newshole, E.A. and Stuart, C. (1973) Regulation in Metabolism, Wiley
- ↑ David L. Nelson, Michael M. Cox (2008), Lehninger Principles of Biochemistry (5th edn), W. H. Freeman and Company
- ↑ Lehninger, A.L. (1975) Biochemistry (2nd edn), Worth