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Mitochondrial hexokinase of rat hepatoma cells in culture: solubilization and kinetic properties

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dc.contributor.author Bustamante, E.
dc.contributor.author Pedersen, P.L.
dc.date.accessioned 2022-10-25T19:54:10Z
dc.date.available 2022-10-25T19:54:10Z
dc.date.issued 1980
dc.identifier.uri https://hdl.handle.net/20.500.12866/12471
dc.description.abstract The highly glycolytic hepatoma cell line H-91 is characterized by a high hexokinase activity relative to rat liver; 50% of this activity is associated with the mitochondrial fraction [Bustamante, E., & Pedersen, P. L. (1977) Proc. Natl. Acad. Sci. U.S.A. 74, 3735-3739], Treatment of mitochondria from this cell line with adenosine 5'-triphosphate (ATP) or glucose 6-phosphate solubilizes bound hexokinase activity. Solubilization of the enzyme by ATP results in a six- to sevenfold purification. Free ATP, unchelated by Mg ions, induces the release of the enzyme from the membrane, whereas the MgATP complex is ineffective. Ethylenediaminetetraacetic acid (EDTA) fails to release mitochondrial hexokinase indicating that the enzyme is not attached to the membrane by divalent cations. Energization of mitochondria is not required for ATP to induce solubilization of bound hexokinase. This is evidenced by (a) the ability of the nonhydrolyzable ATP analogue adenylyl imidodiphosphate to solubilize the enzyme, (b) the inability of uncouplers and inhibitors of oxidative phosphorylation to either solubilize or prevent the release of mitochondrial hexokinase, and (c) the inability of atractyloside to solubilize or prevent the release of bound hexokinase. The bound and the ATP-solubilized forms of mitochondrial hexokinase from H-91 hepatoma cells are kinetically different. When membrane bound, the enzyme has a significantly higher apparent affinity (Km = 0.25 mM) for its substrate MgATP than when solubilized (Km = 1.2 mM). Free ATP acts as a competitive inhibitor of mitochondrial hexokinase. Both the membrane-bound and the solubilized forms of mitochondrial hexokinase have about the same apparent affinity for glucose (Km = 56 and 83 μM, respectively). The experiments reported here provide the first description of the properties and the nature of binding of mitochondrial hexokinase from a tumor cell line growing in tissue culture. en_US
dc.language.iso eng
dc.publisher American Chemical Society
dc.relation.ispartofseries Biochemistry
dc.rights info:eu-repo/semantics/restrictedAccess
dc.rights.uri https://creativecommons.org/licenses/by-nc-nd/4.0/deed.es
dc.subject Adenosine Triphosphate en_US
dc.subject Animal experiment en_US
dc.subject Cell Line en_US
dc.subject Edetic Acid en_US
dc.subject Glucosephosphates en_US
dc.subject Hexokinase en_US
dc.subject In vitro study en_US
dc.subject Liver cell carcinoma en_US
dc.subject Liver Neoplasms, Experimental en_US
dc.subject Magnesium en_US
dc.subject Mitochondria, Liver en_US
dc.subject Mitochondrion en_US
dc.subject Rats en_US
dc.subject Solubility en_US
dc.title Mitochondrial hexokinase of rat hepatoma cells in culture: solubilization and kinetic properties en_US
dc.type info:eu-repo/semantics/article
dc.identifier.doi https://doi.org/10.1021/bi00563a006
dc.relation.issn 0006-2960

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