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1.
de Assis GP Silva CE Stefanon I Vassallo DV 《Comparative biochemistry and physiology. Toxicology & pharmacology : CBP》2003,134(3):375-383
Personal exposure to mercury vapor and the release of mercury from or during removal of amalgam dental fillings increases its blood and plasma concentration. However, it is not known if these very small amounts affect cardiac function. The effects of continuous exposure to 5 and 20 nM of HgCl(2) on the cardiac contractility were investigated in isometric and tetanic contractions of right ventricular strips and in Langendorff perfused rat hearts. The continuous exposure for 2 h produced a small but significant reduction of the isometric twitch force and time to peak tension shortened. Relative post-rest potentiation was not affected by this concentration of HgCl(2) suggesting a lack of action of the metal on the sarcoplasmic reticulum activity. Tetanic tension, in contrast to twitch force, was intensively reduced suggesting an important depressant action on the activity of contractile proteins. In perfused hearts beating spontaneously, isovolumic systolic pressure reduced progressively and the diastolic pressure increased. Although occurring heart rate reduction, it was similar for both controls and mercury treated hearts. Also, time dependent changes in coronary perfusion pressure were similar to controls. Results suggested that cardiac effects may be observed after continuous exposure to very small concentrations of mercury, probably as a result of the cell capacity to concentrate mercury. These results also indicate that continuous professional exposure to mercury followed by its absorption might have toxicological consequences affecting cardiac function, and being considered hazardous. 相似文献
2.
Changes in carp myosin ATPase induced by temperature acclimation 总被引:8,自引:0,他引:8
G. C. Hwang S. Watabe K. Hashimoto 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1990,160(3):233-239
Summary Myosins were isolated from dorsal ordinary muscles of carp acclimated to 10°C and 30°C for a minimum of 5 weeks and examined for their ATPase activities. Ca2+-ATPase activity was different between myosins from cold-and warm-acclimated carp, especially at KCl concentrations ranging from 0.1 to 0.2 M, when measured at pH 7.0. The highest activity was 0.32 mol Pi·min-1·mg-1 at 0.2 M KCl for cold-acclimated carp and 0.47 mol Pi·min-1·mg-1 at 0.1 M KCl for warm-acclimated fish. The pH-dependency of Ca2+-ATPase activity at 0.5 M KCl for both carp was, however, similar exhibiting two maxima around 0.3 mol Pi·min-1·mg-1 at pH 6 and 0.4 mol Pi·min-1·mg-1 at pH 9. K+(EDTA)-ATPase activity at pH 7.0 neither exhibited differences between both myosins. It increased with increasing KCl concentration showing the highest value of about 0.4 mol Pi·min-1·mg-1 at 0.6–0.7 M KCl. Actin-activated myosin Mg2+-ATPase activity was markedly different between cold-and warm-acclimated carp. The maximum initial velocity was 0.53 mol Pi·min-1·mg-1 myosin at pH 7.0 and 0.05 M KCl for cold-acclimated carp, which was 1.6 times as high as that for warm-acclimated carp. These differences were in good agreement with those obtained with myofibrillar Mg2+-ATPase activity between both carp. No differences were, however, observed in myosin affinity to actin. Differences in myosin properties between cold- and warm-acclimated carp were further evidenced by its thermal stability. The inactivation rate constant of myosin Ca2+-ATPase was 25·10-4·s-1 at 30°C and pH 7.0 for cold-acclimated carp, which was about 4 times as high as that for warm-acclimated carp. Light chain composition did not differ between both carp myosins. The differences in a primary structure of the heavy chain subunit was, however, clearly demonstrated between both myosins by peptide mapping.Abbreviations
ATPase
adenosine 5-triphosphatase
-
DTNB 5,5
dithio-bis-2-nitrobenzoic acid
-
DTT
dithiothreitol
-
EGTA
ethyleneglycol bis (-aminoethylether)-N,N,N,N-tetraacetic acid
-
K
D
inactivation rate constant
-
SDS
sodium dodecyl sulfate
-
SDS-PAGE
SDS-polyacrylamide gel electrophoresis 相似文献
3.
Characteristics of ATPase activity and the subunit composition of myosin in the conduction system of bovine heart 总被引:1,自引:0,他引:1
The ATPase activity, light chains and isoenzymes of myosin from specialized myocardial tissue (the A-V node, bundle of His, and right and left bundle branches) of bovine heart were compared with those of atrial and ventricular myosins. The order of Ca2+-activated ATPase activity was atrial greater than specialized myocardial tissue greater than ventricular myosin. SDS-polyacrylamide gel electrophoresis showed that myosin from the specialized myocardial tissue contained the light chains of both atrial and ventricular myosins. On the other hand, the specialized myocardial tissue contained one V3 isomyosin and showed no difference from ventricular myocardial tissue on pyrophosphate gel. 相似文献
4.
Bart I. Roman Sigrid Verhasselt Christophe W. Mangodt Olivier De Wever Christian V. Stevens 《Bioorganic & medicinal chemistry letters》2018,28(13):2261-2264
(S)-Blebbistatin is a micromolar myosin II ATPase inhibitor that is extensively used in research. In search of analogs with improved potency, we have synthesized for the first time C-ring modified analogs. We introduced hydroxymethyl or allyloxymethyl functionalities in search of additional favorable interactions and a more optimal filling of the binding pocket. Unfortunately, the resulting compounds did not significantly inhibit the ATPase activity of rabbit skeletal-muscle myosin II. This and earlier reports suggest that rational design of potent myosin II inhibitors based on the architecture of the blebbistatin binding pocket is an ineffective strategy. 相似文献
5.
Alexandre F. R. Stewart Blanca Camoretti-Mercado David Perlman Madhu Gupta Smilja Jakovcic Radovan Zak 《Journal of molecular evolution》1991,33(4):357-366
Summary We have isolated and characterized five overlapping clones that encompass 3.2 kb and encode a part of the short subfragment 2, the hinge, and the light meromyosin regions of the myosin heavy chain rod as well as 143 bp of the 3 untranslated portion of the mRNA. Northern blot analysis showed expression of this mRNA mainly in ventricular muscle of the adult chicken heart, with trace levels detected in the atrium. Transient expression was seen in skeletal muscle during development and in regenerating skeletal muscle following freeze injury. To our knowledge, this is the first report of an avian ventricular myosin heavy chain sequence. Phylogenetic analysis indicated that this isoform is a distant homolog of other ventricular and skeletal muscle myosin heavy chains and represents a distinct member of the multigene family of sarcomeric myosin heavy chains. The ventricular myosin heavy chain of the chicken is either paralogous to its counterpart in other vertebrates or has diverged at a significantly higher rate.Department of Pharmacological and Physiological Sciences, The University of Chicago, Chicago, IL60637, USA 相似文献
6.
Tiago T Ramos S Aureliano M Gutiérrez-Merino C 《Biochemical and biophysical research communications》2006,342(1):44-49
Treatment of F-actin with the peroxynitrite-releasing agent 3-morpholinosydnonimine (SIN-1) produced a dose-dependent F-actin depolymerization. This is due to released peroxynitrite because it is not produced by 'decomposed SIN-1', and it is prevented by superoxide dismutase concentrations efficiently preventing peroxynitrite formation. F-actin depolymerization has been found to be very sensitive to peroxynitrite, as exposure to fluxes as low as 50-100nM peroxynitrite leads to nearly 50% depolymerization in about 1h. G-actin polymerization is also impaired by peroxynitrite although with nearly 2-fold lower sensitivity. Exposure of F-actin to submicromolar fluxes of peroxynitrite produced cysteine oxidation and also a blockade of the ability of actin to stimulate myosin ATPase activity. Our results suggest that an imbalance of the F-actin/G-actin equilibrium can account for the observed structural and functional impairment of myofibrils under the peroxynitrite-mediated oxidative stress reported for some pathophysiological conditions. 相似文献
7.
Ito K Kashiyama T Shimada K Yamaguchi A Awata Jy Hachikubo Y Manstein DJ Yamamoto K 《Biochemical and biophysical research communications》2003,312(4):958-964
The mechanism and structural features that are responsible for the fast motility of Chara corallina myosin (CCM) have not been elucidated, so far. The low yields of native CCM that can be purified to homogeneity were the major reason for this. Here, we describe the expression of recombinant CCM motor domains, which support the fast movement of actin filaments in an in vitro motility assay. A CCM motor domain without light chain binding site moved actin filaments at a velocity of 8.8 microm/s at 30 degrees C and a CCM motor domain with an artificial lever arm consisting of two alpha-actinin repeats moved actin filaments at 16.2 microm/s. Both constructs displayed high actin-activated ATPase activities ( approximately 500 Pi/s/head), which is indicative of a very fast hydrolysis step. Our results provide an excellent system to dissect the specific structural and functional features that distinguish the myosin responsible for fast cytoplasmic streaming. 相似文献
8.
Kim Y Lucas CA Zhong WW Hoh JF 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2007,177(6):701-705
Ventricular myosin in eutherian mammals undergoes a perinatal change in response to a sharp rise in thyroid hormone levels
during development. In this investigation, changes in ventricular myosin heavy chains (MyHCs) of the tammar wallaby (Macropus eugenii) from early pouch life to adulthood were analysed using native gel electrophoresis, SDS-PAGE and western blotting. Adult
wallaby ventricle showed three myosin isoenzymes, V1, V2 and V3; western blots using specific anti-α-MyHC and anti-β-MyHC antibodies showed their MyHC compositions to be αα, αβ and ββ,
respectively. Ventricular muscle in early pouch joeys expressed predominantly β-MyHC. Up to 200 days, the time of initial
pouch exit, α-MyHC content was around 5%. Thereafter, there was a sharp increase of α-MyHC expression to 35% by 242 days of
age, eventually falling back to 23% in the adult. These changes correlate with known surges in plasma levels of thyroid hormones
around pouch exit. The results suggest that ventricular myosins in a marsupial mammal also undergo a developmental change,
and that marsupial ventricular myosins are thyroid responsive as in eutherians. The increased α-MyHC expression empowers the
heart to meet the enhanced cardiovascular demands of out-of-pouch activity and the thermogenic action of thyroid hormones. 相似文献
9.
Indirect immunofluorescence was used to localize embryonic myosin heavy chains in soleus, adductor longus, tibialis anterior, plantaris, and extensor digitorum longus muscles of 6-month-old rats. A monoclonal antibody (2B6), specifically recognizing rat embryonic myosin, was applied to unfixed, transverse, frozen sections. The number of embryonic myosin-positive (EMP) extrafusal fibers was expressed as a percentage of the total number of fibers. EMP extrafusal fibers were only seen in the soleus and adductor longus muscles, both postural muscles. Approximately 1% of the soleus muscle fibers appeared positively stained for embryonic myosin. The majority of such fibers had a small diameter (<500 ), appeared intensely fluorescent, and typically contained central nuclei. Re-expression of embryonic myosin due to spontaneous fiber denervation is not a likely factor in this study, since alpha-bungarotoxin and N-CAM localization were restricted to the motor end-plate region of EMP fibers. Since embryonic myosin was shown to disappear in all normal-sized myofibers by 2 to 3 months of age, the results suggest that the EMP extrafusal fibers seen in postural muscles of 6 to 12-month-old animals are regenerating myofibers. We speculate that a small number of muscle fibers may be regenerating in normal, adult postural muscles, in response to fiber damage possibly caused by excessive recruitment or overloading. 相似文献
10.
Surath K. Banerjee George J. Kaldor Sandra L. Livernois 《Molecular and cellular biochemistry》1988,83(1):55-63
Summary Subfragment-1 of rabbit atrial and thyrotoxic ventricular myosin (V1 isomyosin) has been prepared and purified by DEAF-cellulose column chromatography. Pyrophosphate-polyacrylamide gel electrophoretic patterns and column chromatographic profile of the atrial subfragment differ from those of thyrotoxic ventricular myosin subfragment-1. On the other hand, Ca2+, Mg2+ and actin-activated ATPase activities of these subfragments are identical. Comparison of the peptide mapping by limited proteolysis in the presence of sodium dodecyl sulfate of the heavy and the light subunits of these subfragments reveals that the patterns for the heavy chain peptides of these subfragments are substantially similar but their light chain peptide patterns differ. The results suggest that the enzymatic and structural similarities that have been recognized between these isoenzymes using intact myosin hold true for the myosin subfragment-1.The differences between these subfragments are due to the differences in the light chains associated with them.Abbreviations EDTA
Ethylene Diamine Tetra-acetic Acid
- SDS
Sodium Dodecyl Sulfate
- S1
myosin subfragment-1
- HC
Heavy Chain
- LC
Light Chain 相似文献
11.
Hideki Ohno Takahito Kondo Yutaka Fujiwara Sei-ichi Tagami Akihiro Kuroshima Yoshikazu Kawakami 《International journal of biometeorology》1991,35(2):111-113
Effects of acute and chronic cold stress on glutathione and related enzymes in rat erythrocytes were investigated. Blood from both cold-acclimated (CA) and cold-adapted (CG) rats had significantly lower concentrations of glutathione than blood from control animals. Superoxide dismutase activity was increased significantly in CA rats and tended to rise in CG rats. Activity of glutathione peroxidase in erythrocytes was inconsistent in that it tended to increase in CA rats but decreased significantly in CG rats. The results may imply that CG rats suffered deleterious effects of hydrogen peroxide. On the other hand, there were marked decreases in glutathione peroxidase and glutathione reductase activities in acutely cold-exposed rats in conjunction with unchanged levels of glutathione. In all treatments the state of riboflavin metabolism was estimated to be adequate, since no increases were observed in the erythrocyte glutathione reductase activity coefficient. 相似文献
12.
Cooke R 《Biophysical reviews》2011,3(1):33-45
Resting skeletal muscle is a major contributor to adaptive thermogenesis, i.e., the thermogenesis that changes in response to exposure to cold or to overfeeding. The identification of the "furnace" that is responsible for increased heat generation in resting muscle has been the subject of a number of investigations. A new state of myosin, the super relaxed state (SRX), with a very slow ATP turnover rate has recently been observed in skeletal muscle (Stewart et al. in Proc Natl Acad Sci USA 107:430-435, 2010). Inhibition of the myosin ATPase activity in the SRX was suggested to be caused by binding of the myosin head to the core of the thick filament in a structural motif identified earlier by electron microscopy. To be compatible with the basal metabolic rate observed in vivo for resting muscle, most myosin heads would have to be in the SRX. Modulation of the population of this state, relative to the normal relaxed state, was proposed to be a major contributor to adaptive thermogenesis in resting muscle. Transfer of only 20% of myosin heads from the SRX into the normal relaxed state would cause muscle thermogenesis to double. Phosphorylation of the myosin regulatory light chain was shown to transfer myosin heads from the SRX into the relaxed state, which would increase thermogenesis. In particular, thermogenesis by myosin has been proposed to play a role in the dissipation of calories during overfeeding. Up-regulation of muscle thermogenesis by pharmaceuticals that target the SRX would provide new approaches to the treatment of obesity or high blood sugar levels. 相似文献
13.
V. Ventrella J.R. Elvir A.R. Borgatti G. Trigari T. Proverbio A. Pagliarani F. Trombetti M. Pirini R. Marín F. Proverbio 《Biochimie》2010
Several tissues from different animals, including the rat kidney and the freshwater rainbow trout gills, show an ouabain-insensitive, furosemide-sensitive, Na+-stimulated ATPase activity, which has been associated with the active control of the cell volume. This Na-ATPase is Mg2+ dependent and it is inhibited by vanadate, which can be taken as an indication that this enzyme is a P-type ATPase. The P-type ATPases are known to form a phosphorylated intermediate during their catalytic cycle, where the phosphate binds an aspartyl residue at the enzyme's substrate site. In the current study, we partially characterized the phosphorylated intermediate of the ouabain-insensitive Na-ATPase of rat kidney cortex homogenates and that of gill microsomes from freshwater rainbow trout. While the kidney cortex homogenates, under our assay conditions, show both Na- and Na,K-ATPase activities, the gill microsomes, when assayed at pH 5.2, only show Na-ATPase activity. Both preparations showed a Mg2+-dependent, Na+-stimulated phosphorylated intermediate, which is enhanced by furosemide. Incubation of the phosphorylated enzyme with 0.6 N hydroxylamine (NH2OH) showed that it is acid-stable and sensitive to hydroxylamine, either when phosphorylated in the presence or absence of furosemide. Addition of ADP to the incubation medium drives the reaction cycle of the enzyme backward, diminishing its phosphorylation. Na+ seems to stimulate both the phosphorylation and the dephosphorylation of the enzyme, at least for the Na-ATPase from gill microsomes. In a E1–E2 reaction cycle of the Na-ATPase, furosemide seems to be blocking the transition step from Na·E1∼P to Na·E2-P. 相似文献
14.
Karasiński J Sokalski A Kilarski W 《Folia histochemica et cytobiologica / Polish Academy of Sciences, Polish Histochemical and Cytochemical Society》2001,39(1):23-28
In the fish heart, ventricular and atrial muscles contain different isoforms of native myosin and myosin heavy chain (MyHC) but the significance of this diversity is still not known. We have analysed ventricular and atrial myocardium of six freshwater fish species (goldfish, roach, bream, rudd, perch and pike-perch) using histochemical staining for myofibrillar ATPase activity as well as non-denaturing and SDS gel electrophoreses for native myosin and MyHC content. In the range of fish species studied, the intensity of ATPase reaction was higher in the atrial myocardium than in the ventricular myocardium and the composition of native myosin isoforms differed between these two muscles. The MyHC content in the cardiac muscle showed some species-related differences. In the goldfish, both atrial and ventricular cardiac muscle contained electrophoretically similar MyHC. In the other fish species, however, the ventricular myocardium showed electrophoretically faster MyHC than that present in the atrial myocardium. These results indicate that there are consistent and characteristic species-related differences between the ventricular and atrial muscles at the level of ATPase staining and the type of MyHC expressed. The findings suggest that fish ventricular and atrial muscles may differ in their contractile properties. 相似文献
15.
I Syrovy 《Physiologia Bohemoslovaca》1984,33(4):376-380
Myosin was isolated from rat and mouse ventricular myocardium and examined during development at stages with known composition of myosin isoenzymes. The ATPase activity and its temperature dependence is the same in one-week-old and adult mouse ventricles. In rat heart myosin, the ATPase activity is low 18 days prenatally, high in 3-week-old animals and declines towards adulthood. ATPase activity of heart myosin from rat foetuses is more temperature dependent than that of three-week-old animals. These results strongly suggest that adaptation of the heart to development differs in the mouse and the rat and that the properties of mouse V1 isoenzyme do not change at the studied periods. 相似文献
16.
Nieznanski K Nieznanska H Skowronek K Kasprzak AA Stepkowski D 《Archives of biochemistry and biophysics》2003,417(2):153-158
We prepared a new type of skeletal myosin subfragment 1 (S1-MLC1F) containing both, the essential and the regulatory light chains, intact, by exchanging the essential light chains of papain S1 with bacterially expressed longer isoform (MLC1F) of this light chain. We then compared the enzymatic and structural properties of chymotryptic S1, papain S1, and S1-MLC1F in the presence and in the absence of Ca(2+) ions bound to the regulatory light chain. In the presence of Ca(2+), subfragment 1 containing both intact light chains exhibited lower V(max) and lower K(m) for actin activation of S1 ATPase. When S1-MLC1F was cross-linked to actin via the N-terminus of the essential light chain, the yield was much higher when Ca(2+) ions saturated the regulatory light chain. Limited proteolysis of the essential light chain in S1-MLC1F was significantly inhibited in the presence of calcium as compared to chymotryptic S1. We conclude that the effect of binding of Ca(2+) to the regulatory light chain is transmitted to the N-terminal extension of the longer isoform of the essential light chain. The resulting structure of the N-terminus is less susceptible to proteolytic digestion, binds tighter to actin, and has an inhibitory effect on actin-activated myosin ATPase. This new conformation of the N-terminus may be responsible for calcium induced myosin-linked modulation of striated muscle contraction. 相似文献
17.
Incubation of inverted plasma membrane vesicles from rat liver with micromolar concentrations of S-dinitrophenylglutathione (DNP-SG) in the presence of ATP resulted in the uptake of DNP-SG into the vesicles. ATP-dependent DNP-SG accumulation was half-maximal with 9 μM DNP-SG, while the Km for ATP was 320 μM. Glutathione disulfide (GSSG), but not reduced glutathione, inhibited the ATP-dependent accumulation of DNP-SG by the vesicles, suggesting that the same, ATP-dependent transport system is responsible for the extrusion of glutathione conjugates and GSSG from liver cells. 相似文献
18.
Mammalian Mrp2 and its yeast orthologue, Ycf1p, mediate the ATP-dependent cellular export of a variety of organic anions. Ycf1p also appears to transport the endogenous tripeptide glutathione (GSH), whereas no ATP-dependent GSH transport has been detected in Mrp2-containing mammalian plasma membrane vesicles. Because GSH uptake measurements in isolated membrane vesicles are normally carried out in the presence of 5-10 mM dithiothreitol (DTT) to maintain the tripeptide in the reduced form, the present study examined the effects of DTT and other sulfhydryl-reducing agents on Ycf1p- and Mrp2-mediated transport activity. Uptake of S-dinitrophenyl glutathione (DNP-SG), a prototypic substrate of both proteins, was measured in Ycf1p-containing Saccharomyces cerevisiae vacuolar membrane vesicles and in Mrp2-containing rat liver canalicular plasma membrane vesicles. Uptake was inhibited in both vesicle systems in a concentration-dependent manner by DTT, dithioerythritol, and β-mercaptoethanol, with concentrations of 10 mM inhibiting by ∼40%. DTT’s inhibition of DNP-SG transport was noncompetitive. In contrast, ATP-dependent transport of [3H]taurocholate, a substrate for yeast Bat1p and mammalian Bsep bile acid transporters, was not significantly affected by DTT. DTT also inhibited the ATP-dependent uptake of GSH by Ycf1p. As the DTT concentration in incubation solutions containing rat liver canalicular plasma membrane vesicles was gradually decreased, ATP-dependent GSH transport was now detected. These results demonstrate that Ycf1p and Mrp2 are inhibited by concentrations of reducing agents that are normally employed in studies of GSH transport. When this inhibition was partially relieved, ATP-dependent GSH transport was detected in rat liver canalicular plasma membranes, indicating that both Mrp2 and Ycf1p are able to transport GSH by an ATP-dependent mechanism. 相似文献
19.
电渗析法进行胱氨酸母液脱盐的研究 总被引:3,自引:0,他引:3
猪毛酸解提取胱氨酸后的母液中含有十七种氨基酸。本文报道了采用我校由辐射法制备的高性能离子交换膜(HF-1及HF-2),通过电渗析技术对母液进行脱盐并制得混合氨基酸。该技术已运转近一年,脱盐率>95.5%,氨基酸中人体必须氨基酸达20%以上。 相似文献
20.
The effect of C-protein on the actin-activated ATPase of column-purified skeletal muscle myosin has been investigated at varied ionic strength. At ionic strengths below about 0.1, C-protein is a potent inhibitor. The inhibition is not reversed by increasing the actin concentration, showing that it is caused by C-protein bound to the myosin filaments. When the ionic strength is raised above about 0.12, on the other hand, the inhibition vanishes and C-protein becomes a mild activator of the actomyosin ATPase. Both effects appear rapidly upon addition of C-protein to pre-formed myosin filaments, so C-protein probably acts by binding to the surface of the filaments. 相似文献