Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.1.1 (hexokinase)
 5,274 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of monovalent (Li+, Cs+) divalent (Cu2+, Ca2+, Sr2+, Ba2+, Zn2+, Cd2+, Hg2+, Pb2+, Mn2+, Fe2+, Co2+, Ni2+) and trivalent (Cr3+, Fe3+, Al3+) metals ions on hexokinase activity in rat brain cytosol were compared at 500 microM. The rank order of their potency as inhibitors of brain hexokinase was: Cr3+ (IC50 = 1.3 microM) greater than Hg2+ = Al3+ greater than Cu2+ greater than Pb2+ (IC50 = 80 microM) greater than Fe3+ (IC50 = 250 microM) greater than Cd2+ (IC50 = 540 microM) greater than Zn2+ (IC50 = 560 microM). However, at 500 microM Co2+ slightly stimulated brain hexokinase whereas the other metal ions were without effect. That inhibition of brain glucose metabolism may be an important mechanism in the neurotoxicity of metals is suggested.
 ...
PMID:Differential effects of monovalent, divalent and trivalent metal ions on rat brain hexokinase. 286 Oct 11

Inhibition of glutamate transport is a potential indirect cause of excitotoxic damage by glutamate in the CNS. The mercuric ion, the form in which metallic mercury vapor is believed to exert its neurotoxic action, is a known inhibitor of amino acid transport. This study examines the specificity with which HgCl2 inhibits glutamate transport in mouse cerebral astrocytes by means of comparative measurements of 2-deoxyglucose uptake. Uptake of 2-deoxyglucose is an index of glucose utilization that reflects the function of Na+,K+-ATPase and hexokinase, and is sensitive to Na+ entry. The kinetic parameters, ionic dependence, and substrate specificity of glutamate transport in these astrocyte cultures were consistent with the commonly occurring system designated X-AG. Acute exposure to 0.5 microM HgCl2 inhibited by 50% the initial rate of glutamate transport but did not affect 2-deoxyglucose uptake. Glutamate transport was not detectably inhibited by Al2+, Pb2+, Co2+, Sr2+, Cd2+, or Zn2+ (10 microM as chlorides). The inhibitory action of 0.5 microM HgCl2 on glutamate transport was rapidly reversible. The action of 1-2 microM HgCl2 was progressive when exposures were extended to 1-3 h, and was more slowly reversible. These results suggest that Hg2+ can impair glial glutamate transport reversibly at exposure levels that do not compromise some other vital cell functions.
 ...
PMID:Specificity and reversibility of the inhibition by HgCl2 of glutamate transport in astrocyte cultures. 289 9

The diastereomers of adenosine 5'-O-(2-thiotriphosphate) (ATP beta S) in the presence of Mg2+, Co2+ and Cd2+ have been used to determine the stereospecificity of the metal-nucleotide binding site of rat muscle hexokinase type II and rat liver glucokinase by the method developed by Jaffe and Cohn [J. Biol. Chem. 254, 10839-10845 (1979)]. The kinetic parameters, Km and V, for the mammalian hexokinase reaction have been determined for ATP beta S in the presence of the three divalent metal ions. In the presence of Mg2+, both enzymes exhibit a preference for the B diastereomer of ATP beta S (V ratio, B/A approximately equal to 20). With Cd+, the stereospecificity is reversed and the A diastereomer is the preferred substrate, suggesting direct coordination of S on the beta-P to this metal ion. Co2+ exhibits a decreased specificity for the B diastereomer over Mg2+. This decreasing order of stereo-specificity for the B isomer reflects primarily the decreasing ratios of nucleotide complexes coordinated to O rather than S on the beta-P as the metal ion is changed from Mg2+ to Co2+ to Cd2+. The kinetic parameters for the hexokinases have also been determined for adenosine 5'-O-(1-thiotriphosphate) (ATP alpha S) using the same three metal ions as activators. The A diastereomer is the preferred substrate regardless of the metal ion. This absence of reversal of stereospecificity for metal-ATP alpha S suggests that the alpha-P is not involved in coordinating the metal on the enzyme, unlike the beta-P. That is, the structural constraints of the ATP-binding site on the enzyme overcome the preferred coordination of Cd2+ to S. Given the greater stability of bidentate metal-ATP complexes over monodentate, these data are interpreted as indicating that MgATP binds to the mammalian hexokinases as the beta gamma-bidentate complex in the A screw sense geometry, as has been found for the yeast hexokinase (Jaffe and Cohn, reference cited above).
 ...
PMID:Metal-nucleotide structure at the active sites of the mammalian hexokinases. 682 73

Low concentrations of metal ions, particularly those of the first row transition series such as Zn2+, Co2+, Mn2+, Ni2+, Cu2+, and, to a lesser extent, the group IIA ions, Ca2+ and Mg2+, promotes binding of carboxypeptidase G2, alkaline phosphatase and yeast hexokinase to immobilized Procion Red H-8BN, Procion Yellow H-A and Cibacron Blue F3G-A respectively. The binding of ovalbumin to immobilized Cibacron Blue F3G-A and Procion Orange MX-G is selectively enhanced in the presence of AI3+. With ovalbumin and alkaline phosphatase, the effect is almost totally specific for both the metal ion and dye, whereas with carboxypeptidase G2 and hexokinase, metal ions such as Co2+, Ni2+, Mn2+, Cu2+, Ca2+ and Mg2+ also promote binding to varying degrees. Almost all other monovalent and trivalent metal ions appear to be ineffective. Metal ion-bound enzymes can subsequently be eluted with appropriate chelating agents of the amine, aminocarboxylate or substituted pyridine classes.
 ...
PMID:Metal ion-promoted binding of proteins to immobilized triazine dye affinity adsorbents. 689 1

Cultured human skin keloid fibroblasts (KFs) showed bioenergetics similar to cancer cells in generating ATP mainly from glycolysis as demonstrated by increased lactate production. Activities of hexokinase, glyceraldehyde-3-phosphate dehydrogenase, and lactate dehydrogenase were also significantly higher compared with normal fibroblasts (NFs). Inhibitors of glycolysis decreased the rate of ATP biosynthesis more significantly in KFs suggesting their reliance on glycolysis. In contrast, ATP generation in NFs was derived mainly from oxidative phosphorylation (OXPHOS), which was more compromised by mitochondrial/respiratory inhibitors. However, when fortified with excess exogenous respiratory substrates, ATP production was increased to a similar maximal level in both types of fibroblasts. In spite of this seemingly equal total capacity, ATP biosynthesis and intracellular ATP concentration were significantly higher in KFs, which further increased their ATP production when exposed to hypoxia and hypoxia-mimetics: desferrioxamine and cobalt chloride. This upregulation was again significantly compromised by glycolytic inhibitors. The rate of generation of reactive oxygen species was lower in KFs possibly due to their switch to aerobic glycolysis from mitochondrial OXPHOS. Thus, cultured skin KFs could provide a human cell model to study the de-regulation of bioenergetics of proliferative cells and their response to the HIF (hypoxia-inducible factor) signaling.
 ...
PMID:Human skin keloid fibroblasts display bioenergetics of cancer cells. 1794 78