Activities of both rat muscle and liver phosphofructokinases are significantly inhibited after a single ethanol intake in the dose of 2.5？g per kg of body weight. This inhibitory effect is indirect, since ethanol in concentration (50？mM) close to that established after 2.5？g per kg of body weight intake cannot decrease their activities in vitro. Inhibition of liver phosphofructokinase activity after the 5.0？g per kg ethanol intake may be direct, since liver phosphofructokinase activity decreases in vitro when ethanol is added to supernatants of rat liver tissue in 100？mM concentration. According to the results of molecular docking, ethanol at high concentrations can be bound by adenine-binding pocket of the allosteric ADP-binding site of liver phosphofructokinase (Asp543, Phe308, Phe538, and Phe671) and its activation by ADP can be blocked by C2H5OH molecule. Direct inhibition of muscle phosphofructokinase activity, probably due to the binding of ethanol to the similar ADP-binding site, is possible when the concentration of ethanol (500？mM) is much higher than the level which can be established in living cells. So, inhibition of muscle phosphofructokinase activity after a single 5.0？g per kg intake is indirect and probably linked with the inhibition of the enzyme by elevated citrate and phosphoenolpyruvate levels. 1. Introduction Phosphofructokinase catalyzes phosphorylation of fructose-6-phosphate to fructose-1,6-bisphosphate. This reaction is a key regulatory step in the glycolysis . Phosphofructokinase activity is regulated through allosteric inhibition and activation. High ATP to ADP ratio inhibits phosphofructokinase and glycolysis as well . Indeed, ADP (the product of the reaction) is an allosteric activator of the activity of that enzyme . Phosphofructokinase is also activated by AMP and fructose-2,6-bisphosphate and inhibited by phosphoenolpyruvate and citrate . Mammalian phosphofructokinase is a tetramer. There are three genes encoding monomers of phosphofructokinase. They are designated as muscle, liver, and platelet phosphofructokinases. The muscle enzyme is a homotetramer (composed of four identical muscle subunits) . Liver also expresses predominantly homotetramer composed of four liver subunits . Ethanol can be found in 163 entries in the Protein Data Bank (http://www.pdb.org/). It can interact with many proteins being a part of the solvent. Alcohol dehydrogenases bind (and metabolize) ethanol specifically . Ethanol also binds α7-nAChRs (nicotinic acetylcholine receptors) as an agonist , GABA receptors
K. Banaszak, I. Mechin, G. Obmolova et al., “The crystal structures of eukaryotic phosphofructokinases from Baker's yeast and rabbit skeletal muscle,” Journal of Molecular Biology, vol. 407, no. 2, pp. 284–297, 2011.
P. Meera, R. W. Olsen, T. S. Otis, and M. Wallner, “Alcohol-and alcohol antagonist-sensitive human GABAA receptors: tracking δ subunit incorporation into functional receptors,” Molecular Pharmacology, vol. 78, no. 5, pp. 918–924, 2010.
H. Ren, A. K. Salous, J. M. Paul, K. A. Lamb, D. S. Dwyer, and R. W. Peoples, “Functional interactions of alcohol-sensitive sites in the N-methyl-D-aspartate receptor M3 and M4 domains,” The Journal of Biological Chemistry, vol. 283, no. 13, pp. 8250–8257, 2008.
G. E. Yevenes, G. Moraga-Cid, A. Avila et al., “Molecular requirements for ethanol differential allosteric modulation of glycine receptors based on selective Gβγ modulation,” The Journal of Biological Chemistry, vol. 285, no. 39, pp. 30203–30213, 2010.
S. W. Kruse, R. Zhao, D. P. Smith, and D. N. M. Jones, “Structure of a specific alcohol-binding site defined by the odorant binding protein LUSH from Drosophila melanogaster,” Nature Structural Biology, vol. 10, no. 9, pp. 694–700, 2003.
A. B. Thode, S. W. Kruse, J. C. Nix, and D. N. M. Jones, “The role of multiple hydrogen-bonding groups in specific alcohol binding sites in proteins: insights from structural studies of LUSH,” Journal of Molecular Biology, vol. 376, no. 5, pp. 1360–1376, 2008.
S. V. Lelevich, V. V. Khrustalev, E. V. Barkovsky, and T. A. Shedogubova, “The influence of ethanol on pyruvate kinases activity in vivo, in vitro, in silico,” American Journal for Medical Biology Research, vol. 1, no. 1, pp. 6–15, 2013.
S. Hassan, B. Duong, K.-S. Kim, and M. F. Miles, “Pharmacogenomic analysis of mechanisms mediating ethanol regulation of dopamine β-hydroxylase,” The Journal of Biological Chemistry, vol. 278, no. 40, pp. 38860–38869, 2003.
R. W. Saeed, S. Varma, T. Peng, K. J. Tracey, B. Sherry, and C. N. Metz, “Ethanol blocks leukocyte recruitment and endothelial cell activation in vivo and in vitro,” Journal of Immunology, vol. 173, no. 10, pp. 6376–6383, 2004.
E. A. Budygin, P. E. M. Phillips, D. L. Robinson, A. P. Kennedy, R. R. Gainetdinov, and R. M. Wightman, “Effect of acute ethanol on striatal dopamine neurotransmission in ambulatory rats,” Journal of Pharmacology and Experimental Therapeutics, vol. 297, no. 1, pp. 27–34, 2001.
Z. Zhong, G. E. Arteel, H. D. Connor et al., “Binge drinking disturbs hepatic microcirculation after transplantation: prevention with free radical scavengers,” Journal of Pharmacology and Experimental Therapeutics, vol. 290, no. 2, pp. 611–620, 1999.
M. Renis, V. Calabrese, A. Russo, A. Calderone, M. L. Barcellona, and V. Rizza, “Nuclear DNA strand breaks during ethanol-induced oxidative stress in rat brain,” FEBS Letters, vol. 390, no. 2, pp. 153–156, 1996.
F. Izbéki, T. Wittmann, S. Csáti, E. Jeszenszky, and J. Lonovics, “Opposite effects of acute and chronic administration of alcohol on gastric emptying and small bowel transit in rat,” Alcohol and Alcoholism, vol. 36, no. 4, pp. 304–308, 2001.
M. M. El-Mas, M. Fan, and A. A. Abdel-Rahman, “Endotoxemia-mediated induction of cardiac inducible nitric-oxide synthase expression accounts for the hypotensive effect of ethanol in female rats,” Journal of Pharmacology and Experimental Therapeutics, vol. 324, no. 1, pp. 368–375, 2008.
A. Undervud and E. Newsholme, “Properties of phosphofructokinase from rat liver and their relation to the control of glycolysis and gluconeogenesis,” Biochemical Journal, vol. 95, no. 7, pp. 868–875, 1965.
R. Huey, G. M. Morris, A. J. Olson, and D. S. Goodsell, “Software news and update a semiempirical free energy force field with charge-based desolvation,” Journal of Computational Chemistry, vol. 28, no. 6, pp. 1145–1152, 2007.
V. V. Khrustalev and E. V. Barkovsky, “Unusual nucleotide content of Rubella virus genome as a consequence of biased RNA-editing: comparison with Alphaviruses,” International Journal of Bioinformatics Research and Applications, vol. 7, no. 1, pp. 82–100, 2011.
K. Tamura, D. Peterson, N. Peterson, G. Stecher, M. Nei, and S. Kumar, “MEGA5: molecular evolutionary genetics analysis using maximum likelihood, evolutionary distance, and maximum parsimony methods,” Molecular Biology and Evolution, vol. 28, no. 10, pp. 2731–2739, 2011.
J. H. Helzberg, M. S. Brown, D. J. Smith, J. C. Gore, and E. R. Gordon, “Metabolic state of the rat liver with ethanol: comparison of in vivo 31phosphorus nuclear magnetic resonance spectroscopy with freeze clamp assessment,” Hepatology, vol. 7, no. 1, pp. 83–88, 1987.
I. V. Deaciuc, N. B. D'Souza, C. H. Lang, and J. J. Spitzer, “Effects of acute alcohol intoxication on gluconeogenesis and its hormonal responsiveness in isolated, perfused rat liver,” Biochemical Pharmacology, vol. 44, no. 8, pp. 1617–1624, 1992.