Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The slow anterior latissimus dorsi (ALD) muscles of newly hatched chickens were transposed and cross0innervated by the mixed, predominantly fast superior brachialis nerve, and investigated 2 to 15 months after the operation. Two months after the operation, myosin ATPase activity of the cross-innervated ALD muscles was still as low as in the control ALD, although the ultrastructure and the histochemical ATPase activity already showed a mixed fibre-type pattern with a predominance of fast -type fibres around the site of nerve implantation. The change of myosin properties of thw whole cross-innervated ALD did not occur until the third month after the operation. At that time, the myosin ATPase activity increased about 2.5 times and light chains of myosin of the fast type appeared in the electrophoretic pattern. The myosin ATPase activity attained 62% of the activity found in the control fast posterior latissimus dorsi muscles at three months; subsequently it remained at about this level reaching 68% 18 months after the operation. The results indicate that approximately two thirds of the cross-innervated ALD muscle fibres became changed towards the fast type under neural influence, whereas about one third remained slow, being re-innervated by the slow-type motor fibres of the implanted nerve.
...
PMID:The onset and progress of transformation of avian slow into fast muscles under neural influence. 12 64

A low myofibrillar ATPase seems to be established definitely in several experimental models of chronic heart hypertrophy as well as in humans, but the biochemical pathogenesis of this defect is still unclear. Three different preparations of myosin were studied. Their purity was estimated by measuring MgATPase or by polyacrylamide gel electrophoresis. The first preparation was highly contaminated by actin and tropomyosin; the second was rather pure, and the third (chromatography on DEAE-Sephadex) was pure but slightly denaturated. Heart myosin CaATPase (ionic strength 0.6 or 0.06) was decreased in chronic aortic insufficiency in the rabbits (CAI) when all three preparations were tested. Two (molecular weight 18,000 and 26,000), sometimes three light subunits were found in heart myosin. Their charge and molecular weight are normal in CAI. The third subunit (molecular weight 15,500) was found in control as well as in CAI. Search for an inhibitor was unsuccessful since the two myosin ATPases are additive. The nucleoprotein peak separated from myosin during chromatography was identical in control and CAI. Therefore, myosin seems to be abnormal in CAI.
...
PMID:Cardiac myosin: preparation, ATPase in chronic heart hypertrophy. 12 56

A purine disulfide analog of ATP, 6,6'-dithiobis(inosinyl imidodiphosphate), forms mixed disulfide bonds between the 6 thiol group on the purine ring and certain key cysteines on myosin, heavy meromyosin, and subfragment one. The EDTA ATPase activities of myosin and heavy meromyosin were completely inactivated when 4 mol of thiopurine nucleotide was bound. When similarly inactivated, subfragment one, depending on its method of preparation, incorporated either 1 or 2 mol of thiopurine nucleotide. Modification of a single cysteine on subfragment one resulted in an inhibition of both the Ca2+ and the EDTA ATPase activities, but the latter always to a greater extent. Modification of two cysteines per head of heavy meromyosin had the same effect suggesting that the active sites were not blocked by the thiopurine nucleotides. Direct evidence for this suggestion was provided by equilibrium dialysis experiments. Heavy meromyosin and subfragment one bound 1.9 and 0.8 mol of [8-3H]adenylyl imidodiphosphate per mol of enzyme, respectively, with an average dissociation constant of 5 X 10(-7) M. Heavy meromyosin with four thiopurine nucleotides bound or subfragment one with two thiopurine nucleotides bound retained 65-80% of these tight adenylyl imidodiphosphate binding sites confirming the above suggestion. Thus previous work assuming reaction of thiopurine nucleotide analogs at the active site of myosin must be reevaluated. Ultracentrifugation studies showed that heavy meromyosin which had incorporated four thiopurine nucleotides did not bind to F-actin while subfragment one with one thiopurine nucleotide bound interacted only very weakly with F-actin. Thus reaction of 6,6'-dithiobis(inosinyl imidodiphosphate) at nucleotide binding sites other than the active sites reduces the rate of ATP hydrolysis and inhibits actin binding. It is suggested that these second sites may function as regulatory sites on myosin.
...
PMID:The covalent modification of myosin's proteolytic fragments by a purine disulfide analog of adenosine triphosphate. Reaction at a binding site other than the active site. 12 13

1. A purified preparation of Ascaris myosin was obtained from the muscle layer of Ascaris lumbricoides suum, using gel filtration and ion-exchange chromatography. 2. Ascaris myosin whether purified or unpurified, had almost the same ability for ATP-splitting and superprecipitation. 3. Ascaris myosin and rabbit skeletal myosin were subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A significant difference in the number of light chains between both myosins was found. Ascaris myosin was found to have one heavy chain and two distinct light chain components (LC1-A and LC2-A), having molecular weights of 18000 and 16000, respectively. These light chains correspond in molecular weight to the light chain 2 (LC2-S) and light chain 3 (LC3-S) in rabbit skeletal myosin. 4. LC1-A could be liberated from the Ascaris myosin molecule reacted with 5,5'-dithio-bis(2-nirobenzoic acid( Nbs2) with recovery of ATPase activity by addition of dithiothreitol. These properties are equivalent to those of the LC2-S in rabbit skeletal myosin, although Ascaris myosin when treated with Nbs2-urea lost its ATPase activity.
...
PMID:Studies on the subunits of myosin from muscle layer of Ascaris lumbricoides suum. 12 18

Intermittent hemodynamic loading of the rat myocardium due to swimming training for several weeks leads to a significant increase in the specific ATPase activity of myosin. This enzymatic alteration of the myosin molecule is accompanied by changes in the stoichiometry of its light chains which are of great significance for the ATPase activity. The maximum shortening velocity of the unloaded myocardium (Vmax), estimated on the basis of afterloaded contractions, shows a slight increase as a result of the physical training. Since, on the other hand, the increase is not significant using the quick release technique, a close relationship between the specific ATPase activity and the augmented cross-sectional contractile capability cannot be proved in our experiments.
...
PMID:[Influence of long-term swimming training on the structure and enzyme activity of myosin in the rat myocardium (author's transl)]. 12 40

Myosin was isolated from leucocytes in horse arterial blood by the same procedures used for the isolation of myosin from skeletal muscle. The Ca2+-, EDTA-, and Mg2+-ATPase [EC 3.6.1.3] activities of the protein was 0.148, 0.147, and 0.001 mumoles/min/mg, respectively, in 0.5 M KCl at pH 7.0 and 25 degrees. The Ca2+-ATPase activity decreased with decrease in the ionic strength. No difference was found between leucocyte myosin and skeletal myosin in the pH profiles of Ca2+- and EDTA-ATPases. The rate and amount of the initial burst of Pi liberation of leucocyte myosin were 0.002 mumoles/min/mg and 0.83 moles/4.8 X 10(5)g, respectively. Leucocyte myosin aggregated into filaments of 0.3 mum length and 150 A diameter, which had a bare shaft and irregular projections. At high ionic strength, the protein bound to skeletal muscle F-actin to form a complex with the characteristic arrowhead structure.
...
PMID:ATPase activity and filament formation of partially purified myosin from leucocytes. 12 90

A histochemical study, using myosin-adenosine triphosphatase activity at pH 9.4, was conducted in soleus and plantaris muscles of adult rats, after bilateral crushing of the sciatic nerve at the sciatic notch. The changes in fiber diameter and per cent composition of type I and type II fibers plus muscle weights were evaluated along the course of denervation-reinnervation curve at 1, 2, 3, 4 and 6 weeks postnerve crush. The study revealed that in the early denervation phase (up to 2 weeks postcrush) both the slow and fast muscles, soleus and plantaris, resepctively, atrophied similarly in muscle mass. Soleus increased in the number of type II fibers, which may be attributed to "disuse" effect. During the same period, the type I fibers of soleus atrophied as much or slightly more than the type II fibers; whereas the type II fibers of plantaris atrophied significantly more than the type I fibers, reflecting that the process of denervation, in its early stages, may affect the two fiber types differentially in the slow and fast muscles. It was deduced that the type I fibers of plantaris may be essentially different in the slow (soleus) and fast (plantaris) muscles under study. The onset of reinnervation, as determined by the increase in muscle weight and fiber diameter of the major fiber type, occurred in soleus and plantaris at 2 and 3 weeks postcrush, respectively, which confirms the earlier hypotheses that the slow muscles are reinnervated sooner than the fast muscles. It is suggested that the reinnervation of muscle after crush injury may be specific to the muscle type or its predominant fiber type.
...
PMID:Denervation and reinnervation of fast and slow muscles. A histochemical study in rats. 12 9

The extent of actin polymerization has been studied for samples in which the bound nucleotide of the actin was ATP, ADP, or an analog of ATP that was not split (AMPPNP). The equilibrium constants for the addition of a monomer to a polymer end were determined from the concentration of monomer coexisting with the polymer. An analysis of these results concludes that the bound ATP on G-actin provides little energy to promote the polymerization of the actin. AMPPNP was incorporated into F-actin and the interaction of F-actin - AMPPNP with myosin was studied. F-actin - AMPPNP activated the ATPase of myosin to the same extent as did F-actin - ADP. However, the rate of superprecipitation was slower in the case of F-actin - AMPPNP than in the control.
...
PMID:The bound nucleotide of actin. 12 84

The reactivity of myosin to [14C]-labeled N-ethylmaleimide ([14C]NEM) or to tritium was determined in functionally different frog muscles. The incorporation of [14C]NEM into myosin decreased during isotonic or isometric contractions, as compared to resting muscle. The cysteine residues which were protected during contraction were not involved in the ATPase activity or the actin-binding ability of myosin. Peptide mapping revealed that several residues were protected simultaneously. The incorporation of tritium into the peptide N-H groups of myosin was also decreased during muscle activity. These data support the idea that activation and subsequent contraction of muscle are correlated with structural changes in the myosin molecule. The reactivity of myosin to [14C]NEM was increased when the muscle was stretched to 140% rest length and treated with iodoacetate to deplete ATP. Based on in vitro experiments and on literature data, it is suggested that in the resting muscle myosin contains bound MgATP which decreases the rate of incorporation of [14C]NEM into myosin and that upon the irreversible loss of ATP the rate increases. 31P nuclear magnetic resonance signals from a number of phosphates were detected in the intact frog muscle. The data indicated that the minimum concentration of ATP in the muscle is 3 mM, a value which agrees with that of chemical determination. The characteristic chemical shifts, coupling constants, and line widths of ATP in the muscle were considerably altered from that of either free ATP in aqueous solutions or ATP in perchloric acid extracts of muscle.
...
PMID:Structural changes in myosin during contraction and the state of ATP in the intact frog muscle. 12 83

The interaction of myosin and paramyosin was investigated by enzymological and ultrastructural techniques. The actin-activated Mg+2 ATPase of rabbit skeletal muscle myosin can be inhibited by clam adductor paramyosin. Both proteins must be rapidly coprecipitated to form filaments for this inhibition. Slowly formed cofilaments are fully activatable by F-actin. In both cases, the cofilaments possess unique structural characteristics when compared to homofilaments. The mode of inhibition appears to be competitive when different concentrations of paramyosin and F-actin are compared. The apparent affinity of the myosin heads for actin is reduced by the presence of paramyosin within rapidly reconstituted thick filaments. These results suggest that paramyosin may serve as part of a relaxing mechanism within invertebrate muscles. It is unlikely that paramyosin plays a role in the initiation and maintenance of catch within specialized molluscan muscles.
...
PMID:Interaction of myosin and paramyosin. 12 90


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---