Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.6.1.3 (ATPase)
 65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In order to study the development of the m. soleus muscle fibers during postnatal ontogenesis in the rat, methods for revealing ATPase activity of myosin at preincubation in acidic and alcaline medium and lactate dehydrogenase and succinate dehydrogenase activity have been used. The m. soleus undergoes three stages of development. The first stage--from birth of the animal up to the 7th day. During this time the muscle is homogenous. The second stage is characterized by appearance of certain histochemical differences in the muscle fibers. The muscle becomes mixed. During the whole period (in males from the 7th up to the 175th, and in females from the 7th up to the 60th-70th day) transferring of glycolytic fibers into oxidative-glycolytic ones with their successive transformation into oxidative fibers is observed. During the third stage (in males older than 175, and in females older than 60-70 days) the m. soleus converts from the mixed into the homogenous one consisting of oxidative fibers.
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PMID:[Growth of different types of muscle fibers of the soleus muscle during postnatal ontogeny in the rat]. 293 93

These studies addressed the question of the in vivo distribution of rat brain hexokinase (HK), and whether physiologically relevant changes in the glycolytic rate are accompanied by changes in the distribution of HK. Homogenates of fresh tissue showed only 11-15% of the overt (assayable without added detergent) HK to be soluble (found in high-speed centrifugation supernatant fractions) when homogenization was begun within 15-20 s of sacrifice. Freeze-blown rat brain tissue also was used, coupled with a new technique wherein it was homogenized as it thawed in a buffered sucrose solution containing 1 mM EDTA. In tissue sampled 15 min (anesthetized) or 60 min (waking) after ip Nembutal injection (40 mg/kg), 23% of the overt HK and 79% of the total lactate dehydrogenase were soluble. The average phosphocreatine content of these and similar homogenates had decreased only 23% from in vivo levels, while ATP had decreased by 65%, due to the combined effects of a high level of endogenous ATPase, chelation of Mg2+ by EDTA, and the greater stability of Mg-ATP2- relative to Mg-ADP1-. These data indicated that the tissue experienced, at most, the equivalent of 6 s of complete ischemia prior to the completion of homogenization. Synaptosomes derived from rat and chicken cerebra were incubated at 37 degrees C in a physiological salt solution containing 10 mM glucose. Addition of veratridine has been shown to stimulate glycolysis and oxidative phosphorylation two- to threefold (H. T. Kyriazi and R. E. Basford (1986) J. Neurochem., in press), but did not alter the HK distribution, as 21% was found in the supernatant fractions of both control and veratridine-stimulated synaptosomes treated with digitonin. These results indicate that in brain tissue, large net movements of HK on and off the outer mitochondrial membrane do not occur, and thus play no role in the regulation of glycolysis.
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PMID:An examination of the in vivo distribution of brain hexokinase between the cytosol and the outer mitochondrial membrane. 294 9

Some indices of erythrocyte metabolism (EM): activity of lactate dehydrogenase (LDH), glucose-6-phosphate dehydrogenase (G-6-PD), glutathione reductase (GR) and common adenosinetriphosphatase (ATPase) activity were studied in 102 patients with acute viral hepatitis (AVH). The suppression of erythrocyte enzymatic activity (EE) was revealed. It was most noticeable at the peak of average and severe AVH. In a decrease of jaundice and during reconvalescence G-6-PD, GR and ATPase activity reduced up to the control level. The suppression of LDH activity was more noticeable, maintained at discharge and was of prognostic value in investigation at early periods of disease in cases of prolonged reconvalescence. Changes in EE activity showed correlation with indices of liver function (levels of certain bilirubin fractions and transaminase activity). In cases of developing deficiency of erythrocyte G-6-PD activity there was a high correlation between a degree of cytolysis and the suppression of erythrocyte LDH activity. The importance of erythrocyte metabolic derangements revealed in AVH pathogenesis was discussed.
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PMID:[Lactate dehydrogenase, glucosephosphate dehydrogenase, glutathione reductase and adenosine triphosphatase activities in the erythrocytes of patients with acute viral hepatitis]. 295 83

The muscle enzymatic changes subsequent to 6 months of strength training followed by 3 months of detraining were examined in 21 physically active men. They were assigned either to a heavy-resistance (HR) or an explosive strength (EX) training program. Muscle biopsies were obtained from m. vastus lateralis for the assessment of activities of the enzymes hexokinase (HK), myofibrillar ATPase (ATPase), citrate synthase (CS), phosphofructokinase (PFK), lactate dehydrogenase (LDH), myokinase (MK) and creatine kinase (CK). The activities were measured on freeze-dried tissue samples using fluorometrical assays. Both groups displayed increased (P less than 0.01-0.001) fast-twitch (FT) fiber area consequent to training with no concomitant hypertrophy of slow-twitch (ST) fiber area. Mean fiber area increased by 16% (P less than 0.001) in HR and 9% (NS) in EX. Following detraining, mean fiber area returned to pretraining value only in EX. HK decreased in both groups (P less than 0.01-0.001) and CK decreased in HR (P less than 0.05). When the two groups were treated together, all enzymes, except for LDH, decreased their activity (P less than 0.05-0.001). It is concluded that 6 months of strength training performed either as heavy-resistance or explosive training is not associated with any increased activities of enzymes reflecting phosphagen, glycolytic, or oxidative metabolism. Instead, the present results suggest that exercise-induced hypertrophy is accompanied by attenuation of certain enzyme activities of importance for ATP regeneration.
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PMID:Enzymatic adaptations consequent to long-term strength training. 295 91

Because of the high degree of filament order in the myofibrils of fish skeletal muscles, and the resulting usefulness of such preparations (particularly flatfish fin muscles) in structural studies of muscular contraction, the fibre type composition of plaice fin muscle has been determined by conventional histochemical tests. As controls, and for comparison, fibre type distributions have also been studied in several other vertebrate skeletal muscles which are widely used for ultrastructural and mechanical studies. In view of the importance of single fibres in such studies and because much of the published information on fibre types is rather difficult to collate, we summarize here the fibre compositions of several muscles; comparable enzyme tests have been carried out on cryostat sections of rabbit psoas muscle, frog sartorius and semitendinosus muscles and plaice fin muscles. On this basis all four muscles are composed of more than one fibre type. We confirm that frog sartorius muscle is mainly a random mixture of two fast fibre types and show that there is also a third group of fibres which are small, metabolically rich and dark under acid m-ATPase tests. We confirm that the semitendinosus is composed of three fibre types, in three non-exclusive, concentric regions and that rabbit psoas muscle contains a mixture of at least three fibre types. The principal new findings of this work are that plaice fin muscle can be divided into four regions, some of which are composed of more than one fibre type, on the basis of its histochemical reactions. This division into regions changes seasonally. The system of classification devised by Dubowitz & Brooke (1973) for mammalian muscle, and which can be applied approximately to frog muscle, can also be applied to the fibres of plaice fin muscle provided that the test for lactate dehydrogenase is carried out in the presence of polyvinyl alcohol. These fibres do not easily fit the division into red, white and intermediate types normally used for fish myotomal muscles. Since none of these muscles is homogeneous, their complex nature must be borne in mind if they are to be used satisfactorily in structural and mechanical studies of muscular contraction involving the use of single fibres.
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PMID:Comparative histochemistry of a flatfish fin muscle and of other vertebrate muscles used for ultrastructural studies. 295 1

Intact synaptosomes isolated from the electric organ of the electric ray Torpedo marmorata contain, at their surface, enzyme activities for the hydrolysis of externally applied nucleoside phosphates. The diazonium salt of sulfanilic acid, as a low-molecular-weight, slowly permeating, covalent inhibitory agent, selectively blocks these enzyme activities and leaves intracellular lactate dehydrogenase intact. The ectoenzymes comprise both a nucleoside triphosphate and diphosphate phosphohydrolase, as well as a 5'-nucleotidase. Activity of nonspecific ectophosphatases is absent. The nucleoside triphosphatase hydrolyzes almost equally well ATP, GTP, CTP, UTP, and ITP and is activated to a similar degree by Mg2+ or Ca2+. It has a high affinity for ATP (Km for ATP in the presence of Mg2+, 75 microM; in the presence of Ca2+, 66 microM). Maximal rates in the presence of Mg2+ and Ca2+ were very similar (34.8 and 32.5 nmol of Pi/min/mg of synaptosomal protein, respectively). Either Mg-ATP or Ca-ATP can act as a true substrate. ADP inhibits hydrolysis of ATP, but AMP is without effect. The nucleoside triphosphatase is not inhibited significantly by a number of inhibitors of mitochondrial Mg2+-ATPase or of Ca2+ + Mg2+-ATPases. It is, however, considerably inhibited by filipin and quercitin. The capacity of intact synaptosomes to hydrolyze also extracellular ADP, GDP, AMP, GMP, and IMP suggests that the nucleoside triphosphatase is part of an enzyme chain that causes complete hydrolysis of the respective nucleoside triphosphate to the nucleoside. We conclude that the cholinergic nerve terminals of the Torpedo electric organ can hydrolyze ATP released on coexocytosis with acetylcholine via an ectonucleoside triphosphatase activity that is different from known endogenous nerve terminal ATPases. The final product of the hydrolysis, adenosine, can then be salvaged by the nerve terminal for resynthesis of ATP. Other possible physiological functions of the ectonucleotidases are discussed.
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PMID:Ectonucleotidase activities associated with cholinergic synaptosomes isolated from Torpedo electric organ. 301 88

Single fibers of rabbit fast-twitch tibialis anterior (TA) muscles were analyzed after continuous low-frequency stimulation for up to 8 wk. After 2-5 wk, every fiber showed higher levels of citrate synthase, hexokinase, and 3-oxoacid CoA-transferase than any control fiber; in some cases these levels were 2-10 times higher (well above any found even in the control soleus, a slow-twitch muscle). Average levels of malate dehydrogenase and alanine transaminase also rose dramatically, but peak single fiber levels were not much above the highest in controls. These differential effects confirm at the single fiber level that chronic stimulation can alter mitochondrial composition. Lactate dehydrogenase, fructose-bisphosphatase, and adenylate kinase declined to levels far below those of any control TA fiber, and, in the case of fructose-bisphosphatase, to within the activity range of control soleus fibers. According to their staining reaction for myofibrillar ATPase, TA fibers were initially 23% type IIA, and 74% type IIB, but by 5 wk these had been converted to a mixture of type I, IIA, and IIC fibers. At 5 wk, levels of lactate dehydrogenase, adenylate kinase, and malate dehydrogenase were characteristic of their (new) ATPase type, but 3-oxoacid CoA transferase had increased to levels 6-15 times higher than in control fibers of the same type.
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PMID:Chronic stimulation of mammalian muscle: enzyme changes in individual fibers. 302 Sep 91

Nucleoside diphosphokinase (NDK) of human platelets has been purified by chromatography on Blue Sepharose CL-6B gel (purification factor of 950) and shown to be free of adenylate kinase, ATPase and adenylate cyclase. The molecular weight was 70,000 with subunits of 17,000. The pH optimum was 8.0 Km values for ATP and dTDP were determined in two ways using the pyruvate kinase-lactate dehydrogenase coupled enzyme assay. Values of 0.38 and 0.20 mM were obtained for ATP and 0.29 and 0.21 mM for dTDP. Km values for ADP (0.024 mM) and GTP (0.12 mM) were determined with the hexokinase-glucose-6-phosphate dehydrogenase coupled enzyme assay. These values are in agreement with those reported for NDK from other sources. Theophylline, which inhibits the NDK activity of intact platelets and platelet membrane preparations and inhibits the ADP-induced shape change of platelets, was shown to be a competitive inhibitor of both the free and phosphorylated forms of NDK with competitive inhibition constants (Kic) of 9.3 and 9.6 mM respectively. Papaverine, another cAMP phosphodiesterase inhibitor, which also inhibits the ADP-induced shape change of platelets, had no inhibitory effect on platelet NDK. It was concluded that the inhibitory effect of theophylline on the activity of the purified enzyme was due to the structural similarity between the methylxanthine and the adenine moiety of ADP.
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PMID:Isolation and kinetic studies of nucleoside diphosphokinase from human platelets and effects of cAMP phosphodiesterase inhibitors. 302 50

The principal effect of cardioactive glycosides (CG) is the inhibition of the (Na+ + K+)-ATPase system with subsequent increase in contractility of the myocardium. In subtoxic and toxic concentrations, CG increase O2 consumption due to a transient Ca2+ overload. Furthermore, the activity of several enzymes of the citrate cycle is changed; cAMP transiently rises with reduction of myocardial ATP, and intracellular lactate dehydrogenase and creatine kinase are lost in the coronary fluid. The antagonistic action of beta-receptor blocking agents is caused by their membrane-stabilizing effect. O2-consumption is increased in the non-failing heart, while in the failing one it decreased. The CG-induced arrhythmias are caused (1) by inhibition of the ATPase system of excitable cardiac structures, and (2) by interaction of CG with the autonomic nervous system. Severe intoxications and the rapid disappearance of cardiac symptoms upon administration of Fab fragments suggest that the CG-induced changes on the molecular level (with the exception of those on the ATPase system) are of secondary significance.
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PMID:Cardiotoxicity of digitalis. 302 25

Within the uterine glands, the following enzymes were demonstrated by histochemical methods after 30, 58, 80, 100, and 110 d of pregnancy, respectively: beta-N-acetyl-hexosaminidase, beta-galactosidase, beta-glucuronidase, alpha-mannosidase, acid phosphatase, alkaline phosphatase, esterases, cytochrome oxidase, 5-nucleotidase, leucine aminopeptidase, adenosine triphosphatase, diaphorases (NADH, NADPH), glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, succinate dehydrogenase, isocitrate dehydrogenase (NAD, NADP), beta-hydroxybutyrate dehydrogenase, glycero-3-phosphate dehydrogenase, NAD-glycero-3-phosphate dehydrogenase, glutamate dehydrogenase (NAD, NADP), lactate dehydrogenase. The results show that the activities of G-6-PDH, 6-PGDH, and cytochrome oxidase increase within secreting cells during the 2nd half of pregnancy. The activities of the other enzymes remained almost unchanged during the period of investigation. The description of our results distinguishes between gland neck, middle, and distal part of the secretory unit, respectively. In general, the enzyme activities are similar within the middle and distal gland segments, but lower in the epithelia of the neck region. The activity of dehydrogenases was medium to intensive within the middle and distal gland segments, but only low to medium within the neck portion. Of the hydrolases, the acid phosphatase, ATPase, leucine aminopeptidase, and beta-galactosidase demonstrated an intensive activity within activity secreting cells. The enzyme activities of the gland epithelia are compared with these of the uterine surface epithelia and the histochemical results are discussed in context with their significance in histiotrophic nutrition.
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PMID:[Enzyme histochemistry of the pig placenta. III. Histotopics of enzymes in the uterine epithelium]. 309 49


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