共查询到19条相似文献,搜索用时 187 毫秒
1.
从多头绒泡菌中纯化了肌球蛋白,并对其亚基组成及ATP酶性质进行了研究。该肌球蛋白是由一种重链(225kD)和两种轻链(20kD,17.5kD)组成的大分子,其亚基之比为HC:LC1:LC2=2:4:2。兔肌F-肌动蛋白能较大激活粘菌肌球蛋白ATP酶活性,Ca^2+离子也能提高其活性,Mg^2+离子无明显影响,钒酸盐,碘乙酸,对氯汞苯甲酸对其ATP酶活性有显著抑制作用。 相似文献
2.
研究了镧、轧、镱及四种配合物对Ca~(2+)-ATP酶活性的影响.结果表明,低浓度的La~(3+),Gd~(3+)和Yb~(3+)对肌质网Ca~(2+)-ATP酶有激活作用;随着其浓度的增加,它们对酶活性的抑制程度增大;而La~(3+),Gd~(3+)和Yb~(3+)对纯化的Ca2~(+)-ATP酶则只有抑制作用;Gd─N─乙酰─缬氨酸和Yb─丙氨酰代丙氨酸配合物对肌质网膜和纯化的Ca~(2+)-ATP酶活性的影响与Gd~(3+)及Yb~(3+)类似,但其激活程度和抑制程度比Gd~(3+)及Yb~(3+)小;Gd─DTPA和Yb-DTPA对Ca2~(+)-ATP酶活性基本无影响。 相似文献
3.
鸭肫平滑肌肌球蛋白的提纯及其ATP酶性质的研究 总被引:1,自引:1,他引:0
从鸭肫肌肉中分离纯化了平滑肌肌球蛋白,并对平滑肌肌球蛋白分子的亚单位组成和平滑肌肌球蛋白的ATP酶性质进行了分析研究。鸭肫平滑肌肌蛋白的Ca^2+-ATP酶活力与溶液的离子强度有关。在低于0.20mol/L的KCL浓度时,酶活力很低;大于0.30mol/L的KCL浓度时,酶活力较高,Ca^2+-ATP酶有两个最适pH值。K^+/EDTA-ATP酶活力随KCL浓度升高而增加。肌动蛋白激活的磷酸化肌球 相似文献
4.
分离了扇贝闭壳肌肌钙蛋白,其分子量为46(InI),40(TnT),和22(TnC)kD。肌球蛋白B含有主要的收缩蛋白质与调节蛋白质,在有Ca^2+和ATP存在时,它会发生超沉淀作用。经低离子强度溶液反复沉淀处理,即失去Ca^2+-敏感性,成为去敏肌球蛋白B。在Ca^2+和ATP作用下,它仍可发生超沉淀作用,但仅及最大活性的50%。若加入肌钙蛋白,则反应活性可完全恢复。兔骨骼肌肌钙蛋白可替代扇贝闭 相似文献
5.
陈明 《中国生物化学与分子生物学报》1997,13(5):556-560
分离了扇贝闭壳肌肌钙蛋白,其分子量为46(InI),40(TnT),和22(TnC)kD.肌球蛋白B含有主要的收缩蛋白质与调节蛋白质,在有Ca2+和ATP存在时,它会发生超沉淀作用.经低离子强度溶液反复沉淀处理,即失去Ca2+-敏感性,成为去敏肌球蛋白B.在Ca2+和ATP作用下,它仍可发生超沉淀作用,但仅及最大活性的50%.若加入肌钙蛋白,则反应活性可完全恢复.兔骨骼肌肌钙蛋白可替代扇贝闭壳肌肌钙蛋白.这表明扇贝闭壳肌兼有肌动蛋白相关调节和肌球蛋白相关调节. 相似文献
6.
联合固氮细菌粪产碱菌(Alcaligenesfaecalis)A1501菌体经超声破碎后,无细胞粗提液以PEG-6000分级沉淀,丙酮沉淀,再经蓝琼脂糖(BlueSepharoseCL-68)亲和层析分离、纯化。获得的纯谷氨酰胺合成酶(GS)在SDS-PAGE和4-30%梯度PAGE上均呈均一的一条带。GS亚基及整酶分子量分别为55kD和645kD,亚基由456个氨基酸残基组成。GS的Km值,在以Glu为氮源的介质中培养时分别为20mmol/L(Glu),50mmol/L(ATP)和45mmol/L(NH~+_4);在以NH~+_4为氮源的介质中培养时则分别为70mmol/L(Glu),49mmol/L(ATP)和80mmol/L(NH~+_4),表明NH~+_4培养下形成高度腺苷化的GS对Glu及NH~+_4的亲和力有所下降。 相似文献
7.
研究了神经节苷脂GM_3参入肌质网膜后Ca~(2+)-ATP酶活力的变化,结果表明:GM_3参入肌质网膜后,对肌质网Ca~(2+)ATP酶活性(ATP水解活力与转运活力)有明显的激活作用.当参入的GM_3浓度为8μmol/L、参入时间为120min、温度为30℃时,对Ca~(2+)-ATP酶的激活作用最大. 相似文献
8.
9.
在有Ca^2+和钙调蛋白存在时,肌球蛋白轻链激酶催化肌球蛋白磷酸化,促使肌动蛋白激活的肌球蛋白(肌动球蛋白)Mg^2+-ATP酶活性显增加,然而,肌旧白磷酸水平化与Mg^2+-ATP酶活性显增加,然而,肌球蛋白磷酸化水平与Mg^2+=ATP酶之间的关系是非线性的,原肌球蛋白可以进一步增加Mg^2+-ATP酶的活性,但仍不改变它们之间的非线性关系,肌球蛋白边激酶的分成肽抑制剂抑制了肌球蛋白磷酸化 相似文献
10.
在有Ca2+和钙调蛋白存在时,肌球蛋白轻链激酶催化肌球蛋白磷酸化,促使肌动蛋白激活的肌球蛋白(肌动球蛋白)Mg2+-ATP酶活性显著增加.然而,肌球蛋白磷酸化水平与Mg2+-ATP酶之间的关系是非线性的,原肌球蛋白可以进一步增加Mg2+-ATP酶的活性,但仍不改变它们之间的非线性关系.肌球蛋白轻链激酶的合成肽抑制剂抑制了肌球蛋白磷酸化和Mg2+-ATP酶活性,并导致平滑肌去膜肌纤维的等长收缩张力与速度的降低.结果提示肌球蛋白轻链激酶参与脊椎动物平滑肌收缩的调节过程,肌球蛋白轻链磷酸化作用会引起平滑肌收缩 相似文献
11.
1. Myosin, actin and the regulatory proteins were prepared from insect flight muscle. 2. The light subunit composition of the myosin differed from that of vertebrate muscle myosin. The ionic strength and pH dependence of the myosin adenosine triphosphatase (ATPase) were measured. 3. Actin was associated with a protein of subunit molecular weight 55000 and was purified by gel filtration. Impure actin had protein bound at a periodicity of about 40nm. 4. Regulatory protein extracts had tropomyosin and troponin components of subunit molecular weight 18000, 27000 and 30000. Crude extracts of regulatory proteins inhibited the ATPase activity of desensitized or synthetic actomyosin; this inhibition was relatively insensitive to high Ca(2+) concentrations. Purified insect regulatory protein produced as much sensitivity to Ca(2+) as did the rabbit troponin-tropomyosin complex. 5. Synthetic actomyosins were made from rabbit and insect proteins. Actomyosins containing insect myosin had a low ATPase activity that was activated by tropomyosin. The Ca(2+) sensitivity of actomyosins containing insect myosin or actin, with added troponin-tropomyosin complex from rabbit, was comparable with that of rabbit actomyosin. 相似文献
12.
A contractile protein closely resembling natural actomyosin (myosin B) of rabbit skeletal muscle was extracted from plasmodia of the slime mold, Physarum polycephalum, by protecting the SH-groups with beta-mercaptoethanol or dithiothreitol. Superprecipitation of the protein induced by Mg2+-ATP at low ionic strength was observed only in the presence of very low concentrations of free Ca2+ ions, and the Mg2+-ATPase [EC 3.6.1.3] reaction was activated 2- to 6-fold by 1 muM of free Ca2+ ions. Crude myosin and actin fractions were separated by centrifuging plasmodium myosin B in the presence of Mg2+-PPi at high ionic strength. The crude myosin showed both EDTA- and Ca2+-activated ATPase activities. The Mg2+-ATPase activity of crude myosin from plasmodia was markedly activated by the addition of pure F-actin from rabbit skeletal muscle. Addition of the F-action-regulatory protein complex prepared from rabbit skeletal muscle as well as the actin fraction of plasmodium caused the same degree of activation as the addition of pure F-actin only in the presence of very low concentrations of Ca2+ ion 相似文献
13.
The regulatory proteins of the myofibril. Characterization and properties of the inhibitory factor (troponin B) 总被引:10,自引:10,他引:0
1. Gel-filtration results indicate that the major component of inhibitory-factor preparations isolated by dissociation of the troponin complex consisted of a protein of subunit weight 23000 daltons. By the same procedure a molecular weight of 18000 was obtained for the calcium-sensitizing factor. 2. The inhibitory factor is specific for the actomyosin type of ATPase and ITPase. It is effective on desensitized actomyosin, natural actomyosin and intact myofibrils. 3. For inhibition, the actomyosin ATPase must be stimulated by Mg(2+), Ca(2+) or Mn(2+). The Co(2+)-, Cd(2+)- or Zn(2+)-stimulated ATPases are not affected. 4. Biological activity is stable to treatment with dissociating agents, heat, pH11, pH1 and carboxymethylation. 5. Increasing amounts of actin, but not myosin or tropomyosin, progressively neutralize the inhibitory activity when added to desensitized actomyosin or myofibrils. 相似文献
14.
Calcium regulation of porcine aortic myosin 总被引:1,自引:0,他引:1
Calcium regulation of actin-activated porcine aortic myosin MgATPase was studied. The MgATPase of the purified actomyosin was stimulated about 10-fold by 0.1 mM Ca2+. The 20,000 molecular weight light chain subunit (LC20) of myosin was phosphorylated by an endogenous kinase that required Ca2+. Half-maximal activation of both kinase and ATPase occurred at about 0.9 microM Ca2+. Phosphorylated and unphosphorylated myosins, free of actin, kinase, and phosphatase, were purified by gel filtration. The MgATPase of phosphorylated myosin was activated by rabbit skeletal muscle actin; unphosphorylated myosin was actin activated to a much lesser extent. Actin activation was maximal in the presence of Ca2+. Regulation of the aortic myosin MgATPase seems to involve both direct interaction of calcium with phosphorylated myosin and calcium activation of the myosin kinase. The MgATPase of trypsin-treated actomyosin did not require Ca2+ for full activity. The trypsin-treated actomyosin was devoid of LC20. When purified unphosphorylated aortic myosin was treated with trypsin, the LC20, was cleaved and the MgATPase, which was not appreciably actin activated before exposure to protease, was increased and was activated by skeletal muscle actin. After incubation of this light chain-depleted myosin with light chain from rabbit skeletal muscle myosin, the actin activation but not the increased activity, was abolished. Unphosphorylated LC20 seems to inhibit actin activation in this smooth muscle. 相似文献
15.
The interactions were analyzed between actin, myosin, and a recently discovered high molecular weight actin-binding protein (Hartwig, J. H., and Stossel, T. P. (1975) J. Biol Chem.250,5696-5705) of rabbit alveolar macrophages. Purified rabbit alveolar macrophage or rabbit skeletal muscle F-actins did not activate the Mg2+ATPase activity of purified rabbit alveolar macrophage myosin unless an additional cofactor, partially purified from macrophage extracts, was added. The Mg2+ATPase activity of cofactor-activated macrophage actomyosin was as high as 0.6 mumol of Pi/mg of myosin protein/min at 37 degrees. The macrophage cofactor increased the Mg2+ATPase activity of rabbit skeletal muscle actomyosin, and calcium regulated the Mg2+ATPase activity of cofactor-activited muscle actomyosin in the presence of muscle troponins and tropomyosin. However, the Mg2+ATPase activity of macrophage actomyosin in the presence of the cofactor was inhibited by muscle control proteins, both in the presence and absence of calcium. The Mg2+ATPase activity of the macrophage actomyosin plus cofactor, whether assembled from purified components or studied in a complex collected from crude macrophage extracts, was not influenced by the presence of absence of calcium ions. Therefore, as described for Acanthamoeba castellanii myosin (Pollard, T. D., and Korn, E. D. (1973) J. Biol. Chem. 248, 4691-4697), rabbit alveolar macrophage myosin requires a cofactor for activation of its Mg2+ATPase activity by F-actin; and no evidence was found for participation of calcium ions in the regulation of this activity.In macrophage extracts containing 0.34 M sucrose, 0.5 mM ATP, and 0.05 M KCl at pH 7.0,the actin-binding protein bound F-actin into bundles with interconnecting bridges. Purified macrophage actin-binding protein in 0.1 M KCl at pH 7.0 also bound purified macrophage F-actin into filament bundles. Macrophage myosin bound to F-actin in the absence but not the presence of Mg2+ATP, but the actin-binding protein did not bind to macrophage myosin in either the presence or absence of Mg2+ATP. 相似文献
16.
T Obinata A Ooi H Takano-Ohmuro 《Comparative biochemistry and physiology. B, Comparative biochemistry》1983,76(3):437-442
Myosin and actin were purified from ascidian smooth muscle. Ascidian myosin contained two classes of light chains and the pH dependence of Ca2+-activated ATPase and the KCl dependence of actin-activated ATPase of ascidian myosin differed from those of vertebrate skeletal myosin. Troponin-tropomyosin complex from ascidian increased the ATPase activity of ascidian reconstituted actomyosin in a Ca2+-dependent manner. Ascidian myosin provided the reconstituted actomyosin with the responsiveness to calcium ions. Two actin isoforms were present in ascidian, which were distinguished by isoelectric points. 相似文献
17.
Purification and characterization of actin-activatable, Ca2+-sensitive myosin II from Acanthamoeba 总被引:11,自引:0,他引:11
Approximately 8-10 mg of highly actin-activatable, CA2+-sensitive Acanthamoeba myosin II can be isolated in greater than 98% purity from 100 g of amoeba by the new procedure described in detail in this paper. The enzyme isolated by this procedure can be activated by actin because its heavy chains are not fully phosphorylated (Collins, J. H., and Korn, E. D. (1980) J. Biol Chem. 255, 8011-8014). We now show that Acanthamoeba myosin II Mg2+-ATPase activity is more highly activated by Acanthamoeba actin than by muscle actin. Also, actomyosin II ATPase is inactive at concentrations of free Mg2+ lower than about 3 mM and fully active at Mg2+ concentrations greater than 4 mM. Actomyosin II Mg2+-ATPase activity is stimulated by micromolar Ca2+ when assayed over the narrow range of about 3-4 mM Mg2+ but is not affected by Ca2+ at either lower or higher concentrations of Mg2+. The specific activity of te actomyosin II Mg2+-ATPase also increases with increasing concentrations of myosin II when the free Mg2+ concentration is in the range of 3-4 mM but is independent of the myosin II concentration at lower or higher concentrations of Mg2+ . This marked effect of the Mg2+ concentration on the Ca2+-sensitivity and myosin concentration-dependence of th specific activity of actomyosin II ATPase activity does not seem to be related to the formation of myosin filaments, and to be related to the formation of myosin filaments, and myosin II is insoluble only at high concentrations of free Mg2+ (6-7 mM) were neither of these effects is observed. Also, the Mg2+ requirements for actomyosin II ATPase activity and myosin II insolubility can be differentially modified by EDTA and sucrose. 相似文献
18.
巨大芽孢杆菌产胞外青霉素酰化酶发酵液经硫酸铵分级抽提及SephadexG-100、羟基磷灰石、DEAE纤维素DE52等层析步骤,提纯了青霉素酰化酶,得到电泳均一的酶制剂。纯酶比活力约为25U/mg蛋白,纯化49倍,活力回收58%,经PAGE及SDS-PAGE测知该酶不含亚基,其分子量约为140kD。该酶最适pH为9.0,最适温度47℃,用底物NIPAB测活,其Km值为6.2×10~(-4)mol/L,Vm值为1.24×104mol/L。此外还探讨了部分金属离子对该酶的影响。 相似文献
19.
The preparation and characterization of a Ca2+-sensitive actomyosin from chicken gizzard is described. The pH curve of the Mg2+ ATPase activity of the actomyosin was dominated by the activity of the myosin component, and this gave rise to the acid and alkaline optima. Skeletal muscle myosin showed a similar curve. Both the activation of myosin ATPase by actin, and the Ca2+ sensitivity were confined to the neutral pH region. The subunit composition of the Ca2+-sensitive actomyosin was interesting in that no components corresponding to skeletal muscle troponin were obvious. It is suggested that the activity of gizzard actomyosin is regulated by a protein on the thin filaments with a subunit weight of ~130,000. 相似文献