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

The organ specificity of creatine kinase, esterase, isocitrate dehydrogenase lactate dehydrogenase, nucleoside phosphorylase, adenylate kinase, hexokinase, malate dehydrogenase, malic enzyme, glucose-6-phosphate dehydrogenase of black-white cattle has been studied. Esterases, creatine kinase, adenylate kinase, hexokinase and glucose-6-phosphate dehydrogenase have a very wide spectrum of the organ variabilities. Liver and heart have the largest specificity of enzymes activity. Some peculiarities of isozyme spectrum are found in ovaries and spleen.
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PMID:[Regularities of organ-specific expression of enzyme systems in cattle]. 148 Dec 59

Kinetic parameters of rat creatine kinase isozymes at different vitamin K supply and treatment with antivitamin K--pelentan have been determined. MM-isozyme (skeletal muscle) has selective sensitivity to the vitamin K deficit, while BB and MB-isozymes (brain, kidney and heart) have not. The value KM for ATP of MM-isozymes increases, while maximal activity decreases. Pelentan treatment does not lead to the change of MM-creatine kinase affinity to ATP. Soluble hexokinase of skeletal muscle in rats with vitamin K deficiency and treated with pelentan has higher affinity to glucose as compared to normal rat enzyme. It has been supposed that skeletal muscle hexokinase exists in a particular molecular form under vitamin K deficiency.
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PMID:[Kinetic characteristics of creatine kinase and hexokinase from rat skeletal muscles during dietary deficit of vitamin K and administration of pelentane]. 151 50

The B-CK isozyme of cytoplasmic creatine kinase is localized distinctly in the terminal web region of the intestinal epithelial cell brush border (Keller and Gordon: Cell Motil. Cytoskeleton 19:169-179, 1991). Experiments were performed to determine whether this CK is energetically coupled to the myosin II that is present in the circumferential ring and interrootlet structural domains of the brush border terminal web. In isolated brush borders, ATP-dependent circumferential ring contraction and interrootlet myosin solubilization were supported either by an exogenous PEP-pyruvate kinase-based ATP-regeneration system (PEP-PK) or by the addition of phosphocreatine to the endogenous B-CK-based ATP-regeneration system (PCr-B-CK). Addition of an exogenous hexokinase-glucose ATP-hydrolysis system (HK-G) effectively blocked both contraction and myosin solubilization in the PEP-PK assay. In contrast, HK-G had no significant effect on PCr-B-CK-supported brush border contraction, although it did inhibit interrootlet myosin solubilization. Thus, when high-energy phosphate is supplied as phosphocreatine, brush border B-CK imparts to the circumferential ring myosin a selective energetic advantage over other ATPases. These results suggest that myosin and B-CK are functionally coupled in the brush border circumferential ring, where they might comprise one end of an energy circuit that supplies energy for contraction, but that colocalization of CK with myosin in the brush border interrootlet domain is insufficient to establish functional coupling.
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PMID:Functional coupling to brush border creatine kinase imparts a selective energetic advantage to contractile ring myosin in intestinal epithelial cells. 153 84

The association of glycolytic enzymes with the particulate fraction of the cell was assessed in the brain of the freshwater turtle, Pseudemys scripta elegans, using three different methodologies. Each method showed that a large percentage of each of eight enzymes was bound in brain. The effect of environmental anoxia (5 or 20 h submergence in N2-bubbled water at 7 degrees C) on the distribution of enzymes between free and bound states was analyzed. All three techniques showed a significant increase in the percentages of brain aldolase and glyceraldehyde-3-phosphate dehydrogenase bound during anoxia and no change in lactate dehydrogenase or creatine kinase binding. Two methodologies also showed an increase in the percent bound during anoxia for hexokinase, phosphofructokinase, and phosphoglycerate kinase. An increased association of glycolytic enzymes with structural elements of the cell during anoxia may physically position the glycolytic pathway to facilitate coupling between this ATP-generating pathway and ATP-utilizing processes, such as membrane ion pumps.
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PMID:Subcellular enzyme binding and the regulation of glycolysis in anoxic turtle brain. 153 98

1. Replacement of fetal calf serum and chicken embryo extract by Ultroser G and rat brain extract during the proliferation phase resulted in a higher maturation grade of cultured rat muscle cells after 7 days of differentiation, on base of the percentage of the muscle specific isoenzyme of creatine kinase (CK-MM). 2. Furthermore, the activities of creatine kinase, citrate synthase, cytochrome c oxidase and hexokinase were significantly higher. 3. Compared to the enzyme activities in m. quadriceps of 10 day-old rat and m. quadriceps, m. soleus and m. extensor digitorum longus of young adult rats, the metabolic capacity of cultured myotubes most closely resembles that of the first muscle. 4. Paralysis with tetrodotoxin caused a slight decrease of the creatine kinase activity and the percentage of CK-MM of cultured myotubes and an increase of the activities of hexokinase, phosphorylase and AMP deaminase. 5. Electrical stimulation performed at different frequencies and time periods had no effect on the enzyme activities of cultured rat muscle cells. 6. Only the AMP deaminase activity was decreased after intense electrical stimulation.
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PMID:Effects of growth medium, electrical stimulation and paralysis on various enzyme activities in cultured rat muscle cells. Comparison with activities in rat muscles in vivo. 159 50

On the basis of the percentage creatine kinase-MM, human skeletal muscle cells cultured on growth and differentiation media containing the serum substitute Ultroser G reach a significantly higher maturation grade after 7 days of differentiation than cells cultured on serum-containing media. They also remain viable for longer periods. The myotubes are much longer, their nuclei are often localized in rows on the periphery, and they show cross-striation more frequently. The activities of creatine kinase, citrate synthase, cytochrome c oxidase, AMP deaminase, and phosphorylase are significantly higher. Extending the differentiation period to 3 weeks increases the maturation grade of the cultures and the activities of all the enzymes mentioned before, except phosphorylase. A correlation exists between the enzyme activities and the maturation grade of the muscle cells. The content of fatty acid-binding protein also increases significantly with the maturation grade in contrast to the palmitate oxidation rate. The AMP deaminase and creatine kinase activity and the percentage MM-type remain lower in cultured cells than in adult muscle and the hexokinase activity remains higher, but the other enzyme activities become comparable after 20 days of differentiation. The myotubes, derived from Ultroser G-containing culture media, show spontaneous contractions after 12 days and cross-striation after 20 days when immunostained for the M-subunit of creatine kinase. These cells possess clusters of acetylcholine receptors, but aggregation of desmin at the site of the clusters was never detectable. The possibility of cultivating muscle cells with a predictable maturation grade allows the study of muscle development and muscular diseases caused by differentiation defects or by deficiency of a maturation-dependent (iso)enzyme.
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PMID:The biochemical and structural maturation of human skeletal muscle cells in culture: the effect of the serum substitute Ultroser G. 164 54

The outer mitochondrial membrane pore at a voltage above 20 to 30 mV can adopt a state of low conductance which may restrict free permeability of mitochondrial substrates. In order to obtain insight into the physiological meaning of this property we took advantage of the fact that the low conductance pore state could be induced by a polyanion in lipid bilayer membranes as well as in intact mitochondria. Upon reconstitution in artificial bilayers the pore in this substate became exclusively cation selective when the polarity of the applied voltage was negative on the cis-side. This behaviour of the pore would explain why induction of the low conductance pore state in intact mitochondria led to a complete inhibition of mitochondrial intermembranous kinases, such as creatine kinase and adenylate kinase, but not of peripheral kinases, for example hexokinase, when utilizing external ATP. The possibility that the inner membrane potential might be transduced to the outer membrane in the contact sites, suggests the existence of cation selective pores in these sites. This aspect may be important in the regulation of peripheral kinases like creatine kinase, nucleoside diphosphate kinase and adenylate kinase which are located behind the outer mitochondrial membrane.
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PMID:The cationically selective state of the mitochondrial outer membrane pore: a study with intact mitochondria and reconstituted mitochondrial porin. 169 May 71

The regulation of intracellular calcium uptake and release in cultured gastric smooth muscle cells was studied in saponin-permeabilized cells derived from the rabbit antrum. Cells were studied in an ATP-regenerating medium in which the value of the ATP-to-ADP ratio was fixed by variation of the relative concentrations of creatine and creatine phosphate in the presence of a constant concentration of adenine nucleotides and creatine kinase. Free calcium in the medium was measured through the use of the fluorescent probe fura-2. As the ratio of ATP/ADP was increased (8.5, 55.0, and 155.0), the rate of calcium sequestration was increased, resulting in a decrease of steady-state free calcium (275.2, 178.4, and 98.1 nM, respectively). The addition of glucose (5 mM) and hexokinase (15 U/ml), which results in an increase of ADP due to the phosphorylation of glucose in the medium, caused an increase of free calcium concentration to a new set point of approximately 400 nM. Mitochondrial blockade with antimycin A before permeabilization had no effect on calcium sequestration or the resultant free calcium concentration, indicating that under physiological conditions calcium is sequestered predominantly into nonmitochondrial storage sites. Specific variation of ATP/ADP had no effect on the concentration dependence of inositol trisphosphate-induced calcium efflux, suggesting the functional independence of intracellular calcium influx and efflux pathways. These results indicate a significant role for cytoplasmic ATP/ADP in the control of intracellular calcium sequestration and the regulation of steady-state calcium concentration in cultured gastrointestinal smooth muscle cells.
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PMID:ATP-dependent control of steady-state cytosolic calcium in cultured gastric smooth muscle. 192 49

We measured creatine kinase (CK, EC 2.7.3.2) activity in serum with a new reagent system utilizing thermostable glucokinase (EC 2.7.1.2). Automated determinations were performed with Toshiba's Model TBA-80S Biochemical Analyzer. Precision studies demonstrated within-run and between-run CVs of 0.4%-2.4% and 2.8%-3.1%, respectively. The response linearity was confirmed for CK activity up to 1000 U/L at 37 degrees C. CK activities correlated well (r = 0.997) with those obtained by the manual method recommended by the German Society for Clinical Chemistry (measuring at 37 degrees C) involving hexokinase (EC 2.7.1.1). However, CK activities measured by our method were consistently higher than those of the hexokinase method at reaction temperatures of 30, 37, and 40 degrees C. These data indicate that the new method with thermostable glucokinase is better than that with thermo-unstable hexokinase for determination of CK activity in serum.
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PMID:Automated determination of creatine kinase activity in serum with use of thermostable glucokinase. 200 55

The rates of glucose phosphorylation by bound hexokinase were investigated in mitochondria isolated from rat brain. Initial rates obtained either with ATP generated from oxidative phosphorylation or with ATP added externally were compared. Our results show that the external ATP supports a 2-3-fold higher hexokinase activity than does ATP generated by oxidative phosphorylation under Stage 3 conditions. ATP formed by mitochondrial creatine kinase in the presence of creatine phosphate also supports higher initial rates of glucose phosphorylation than does oxidative phosphorylation. The data suggest that concentrations of ATP present in the cytosol of normal tissue will probably maintain higher rates of glucose phosphorylation than ATP being exported directly from the mitochondrial matrix at maximal State 3 rates.
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PMID:Hexokinase bound to rat brain mitochondria uses externally added ATP more efficiently than internally generated ATP. 200 76


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