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 outer mitochondrial membranes of all organisms so far examined contain a protein which forms voltage-dependent anion selective channels (VDAC) when incorporated into planar phospholipid membranes. Previous reports have suggested that the yeast (Saccharomyces cerevisiae) outer mitochondrial membrane component responsible for channel formation is a protein of 29,000 daltons which is also the major component of this membrane. In this report, we describe the purification of this 29,000-dalton protein to virtual homogeneity from yeast outer mitochondrial membranes. The purified protein readily incorporates into planar phospholipid membranes to produce ionic channels. Electrophysiological characterization of these channels has demonstrated they have a size, selectivity and voltage dependence similar to VDAC from other organisms. Biochemically, the purified protein has been characterized by determining its amino acid composition and isoelectric point (pI). In addition, we have shown that the purified protein, when reconstituted into liposomes, can bind hexokinase in a glucose-6-phosphate dependent manner, as has been shown for VDAC purified from other sources. Since physiological characterization suggests that the functional parameters of this protein have been conserved, antibodies specific to yeast VDAC have been used to assess antigenic conservation among mitochondrial proteins from a wide number of species. These experiments have shown that yeast VDAC antibodies will recognize single mitochondrial proteins from Drosophila, Dictyostelium and Neurospora of the appropriate molecular weight to be VDAC from these organisms. No reaction was seen to any mitochondrial protein from rat liver, rainbow trout, Paramecium, or mung bean. In addition, yeast VDAC antibodies will recognize a 50-kDa mol wt protein present in tobacco chloroplasts.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Purification and characterization of the voltage-dependent anion channel from the outer mitochondrial membrane of yeast. 244 71

High-performance liquid chromatography (HPLC) coupled to an electrochemical detector in an oxidative mode was used to analyze purine bases, nucleosides, and nucleotides as well as restriction fragments of nucleic acids. Ligands were separated by liquid chromatography with electrochemical detection (LC-EC) using size exclusion, ion-exchange, or reverse phase techniques. Using an amperometric electrochemical detector the determination was characterized with respect to sensitivity, selectivity, and capacity factor. It was observed from hydrodynamic and cyclic voltammetry that the optimum oxidation potential differed for the three major classes of purines, permitting an enhancement in selectivity when compared to detection. Guanylyl moieties demonstrated a half-wave potential at 0.800 V vs Ag/AgCl, while those for the adenylyl and inosylyl groups are above 1,000 V vs Ag/AgCl. The facility of the method to analyze components of a complex biological milieu was demonstrated by examining the purine pools of crude and partially purified eye lens homogenates as well as by comparing the traditional hexokinase assay to the newly developed LC-EC technique. Additionally, LC-EC was compared to detection for determination of the purine-metabolizing enzyme activities, adenylate deaminase and adenylosuccinate synthetase from crude cellular lysates of the cellular slime mold, Dictyostelium discoideum. Finally, the technique was used to assay the fragments from lambda-DNA cut with the restriction endonuclease Pst-1.
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PMID:LC-EC determination of nucleotides and nucleic acids: application to enzyme assays and the analysis of DNA fragments. 283 15

Hexokinase is the first enzyme involved in glycolysis in most organisms, including the etiological agents of Chagas disease (Trypanosoma cruzi) and African sleeping sickness (Trypanosoma brucei). The T. cruzi enzyme is unusual since, unlike the human enzyme, it is inhibited by inorganic diphosphate (PPi). Here, we show that non-hydrolyzable analogues of PPi, bisphosphonates, are potent inhibitors of T. cruzi hexokinase (TcHK). We determined the activity of 42 bisphosphonates against TcHK, and the IC(50) values were used to construct pharmacophore and comparative molecular similarity indices analysis (CoMSIA) models for enzyme inhibition. Both models revealed the importance of electrostatic, hydrophobic, and steric interactions, and the IC(50) values for 17 active compounds were predicted with an average error of 2.4x by using the CoMSIA models. The compound most active against T. cruzi hexokinase was found to have a 2.2 microM IC(50) versus the clinically relevant intracellular amastigote form of T. cruzi, but only a approximately 1-2 mM IC(50) versus Dictyostelium discoideum and a human cell line, indicating selective activity versus T. cruzi.
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PMID:Inhibition of Trypanosoma cruzi hexokinase by bisphosphonates. 1639 6

The differentiation-inducing factor-1 (DIF-1) is a signal molecule that induces stalk cell formation in the cellular slime mold Dictyostelium discoideum, while DIF-1 and its analogs have been shown to possess antiproliferative activity in vitro in mammalian tumor cells. In the present study, we investigated the effects of DIF-1 and its analogs on normal (nontransformed) mammalian cells. Without affecting the cell morphology and cell number, DIF-1 at micromolar levels dose-dependently promoted the glucose uptake in confluent 3T3-L1 fibroblasts, which was not inhibited with wortmannin or LY294002 (inhibitors for phosphatidylinositol 3-kinase). DIF-1 affected neither the expression level of glucose transporter 1 nor the activities of four key enzymes involved in glucose metabolism, such as hexokinase, fluctose 6-phosphate kinase, pyruvate kinase, and glucose 6-phosphate dehydrogenase. Most importantly, stimulation with DIF-1 was found to induce the translocation of glucose transporter 1 from intracellular vesicles to the plasma membranes in the cells. In differentiated 3T3-L1 adipocytes, DIF-1 induced the translocation of glucose trasporter 1 (but not of glucose transporter 4) and promoted glucose uptake, which was not inhibited with wortmannin. These results indicate that DIF-1 induces glucose transporter 1 translocation and thereby promotes glucose uptake, at least in part, via a inhibitors for phosphatidylinositol 3-kinase/Akt-independent pathway in mammalian cells. Furthermore, analogs of DIF-1 that possess stronger antitumor activity than DIF-1 were less effective in promoting glucose consumption, suggesting that the mechanism of the action of DIF-1 for stimulating glucose uptake should be different from that for suppressing tumor cell growth.
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PMID:Dictyostelium differentiation-inducing factor-1 induces glucose transporter 1 translocation and promotes glucose uptake in mammalian cells. 1755 62