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1.
《The International journal of biochemistry》1994,26(7):905-911
- 1.1. Parotid plasma membrane nonpump low-affinity Ca2+-ATPase, which possesses high-affinity (Ca2+ + Mg2+ )-ATPase activity, was characterized.
- 2.2. Purified Ca2+-ATPase hydrolyzed the nucleoside triphosphates, GTP, ITP, CTP, UTP, TTP (67–93% of ATP) and nucleoside diphosphates, ADP. GDP, IDP, CDP, TDP (12–40% of ATP) but not AMP and p-NPP.
- 3.3. The maximum activities of Ca2+- and (Ca2+ +Mg2+ )-ATPases were obtained in the presence of 1 mM and 0.13 μ M Ca2+, respectively.
- 4.4. The Km values for Ca2+ in Ca2+- and (Ca2++ Mg2+ )-ATPases were 0.2 mM and 22 nM. respectively.
- 5.5. The activities of both Ca2+- and (Ca2+ + Mg2+ )-ATPases were found in the right-side-out-vesicles obtained from the plasma membrane-rich fraction.
- 6.6. These features suggest that Ca2+-ATPase is an ecto-Ca2+-dependent nucleoside triphosphatase.
2.
《Comparative biochemistry and physiology. B, Comparative biochemistry》1990,95(2):383-390
- 1.1. Homogenates of gills from the freshwater shrimp M. amazonicum exhibit the following ATPase activities: (i) a basal, Mg2+-dependent ATPase; (ii) an ouabain-sensitive, Na+ + K+-stimulated ATPase; (iii) an ouabain-insensitive, Na+-stimulated ATPase; and (iv) an ouabain-insensitive, K+-stimulated ATPase.
- 2.2. K+ suppresses the Na+-stimulated ATPase activity in a mixed-type kind of inhibition, whereas Na+ does not exert any noticeable effect on the K+-stimulated ATPase activity.
- 3.3. The Na+- and the K+-stimulated ATPase activities are totally inhibited by 5 mM ethacrynic acid in the incubation medium.
- 4.4. The Na+- and the K+-stimulated ATPase activities are not expressions of the activation of a Ca-ATPase.
- 5.5. The possible localization and roles of the described ATPases within the gill epithelium are briefly discussed and evaluated.
3.
《The International journal of biochemistry》1994,26(2):287-293
- 1.1. Evidence was obtained that activities of both low-affinity Ca2+-ATPase and high-affinity (Ca2+ + Mg2+)-ATPase in the plasma membrane-rich fraction from bovine parotid gland reside on the same enzyme.
- 2.2. Two solubilized ATPases were purified by four steps of HPLC; and both activities eluted at the same fractions from each column, and the specific activity ratio of the two enzymes at each step was constant.
- 3.3. By non-denaturing PAGE, the final preparation gave a single band for both protein staining and activity staining for the two ATPases; and the Ca2+-ATPase activity comigrated with that of (Ca2+ + Mg2+)-ATPase.
- 4.4. In SDS-PAGE, each activity staining for the ATPases also gave a single band, and both activities comigrated.
- 5.5. These findings suggest that Ca2+-ATPase and (Ca2+ + Mg2+)-ATPase are a single enzyme.
4.
《Comparative biochemistry and physiology. A, Comparative physiology》1993,104(2):309-312
- 1.1. The objective of the present study was to determine the effect of age and taurine on chick B cell calcium uptake and membrane (Ca2+ + Mg2+)-ATPase activity in 1–4-week-old chicks.
- 2.2. The calcium uptake rate decreased with age (P < 0.05) and was further decreased by taurine (P < 0.05).
- 3.3. (Ca2+ + Mg2+)-ATPase activity increased with age (P < 0.05) and was stimulated by taurine (P < 0.05).
- 4.4. The data demonstrate that the flux of calcium across the B-cell membrane changes during early post-hatch development, and that taurine regulates both the influx and efflux of calcium in chick B-cells.
5.
《The International journal of biochemistry》1993,25(8):1115-1120
- 1.1. The inhibition kinetics of sheep brain butyrylcholinesterase (BChE) (acylcholine acylhydrolase, EC 3.1.1.8) by Cd2+ and Zn2+ has been studied.
- 2.2. Ks has been determined as 0.14mM. Cd2+ and Zn2+ were the hyperbolic mixed-type inhibitors of BChE. Ca2+ and Mg2+ had no effect on the enzyme activity in the experimental conditions.
- 3.3. But when the enzyme was inhibited by 0.1 mM Cd2+ or Zn2+, Ca2+ and Mg2+ reactivated the inhibited form of BChE.
6.
《Comparative biochemistry and physiology. B, Comparative biochemistry》1981,68(3):435-439
- 1.1. Smooth myosin B and myosin A were prepared from dog colon and their enzymatic properties were studied.
- 2.2. Colonic myosin B with two light chain corresponding to L2 and L3 in skeletal myosin showed much lower ATPase activities than rabbit skeletal myosin B.
- 3.3. The Mg2+-ATPase of myosin B was activated at high magnesium concentrations with the maximum activation between 10−3 and 10−2M and showed only a slight dependence on KCl concentration. On the other hand, Mg2+-ATPase activity of myosin A decreased with decreasing KCI concentration, suggesting the activation by actin of colonic myosin ATPase as much as skeletal myosin ATPase.
- 4.4. The pH dependence of Ca2+-ATPase showed a U-shaped curve although above pH 8.5 the activity was suppressed rapidly. The activity-ionic strength curve indicated that Ca2+- and ethylenediamine-tetraacetic acid (EDTA)-ATPase activities increased with increasing KCI concentration.
- 5.5. Mg2+-ATPase was fairly stable to urea treatment, whereas EDTA- and Ca2+-ATPase were activated by a low concentration of urea, followed by an inhibition.
- 6.6. These results were discussed as compared with those of skeletal myosin B.
7.
《Comparative biochemistry and physiology. B, Comparative biochemistry》1991,98(4):753-758
- 1.1. In the plasma membrane of mussel gill cells an ouabain insensitive, Ca2+-activated ATPase activity is present. The ATPase has high Ca2+ affinity (Kma = 0.3 μM).
- 2.2. The optimum assay conditions to evaluate the enzymatic activity of the Ca2+-stimulated ATPase at 19°C are: 120–300 mM KCl ionic strength, pH 7.0 and 2 mM ATP. As for mammalian enzymes, the Ca2+ ATPase activity is stimulated by DTT (0.5–1 mM) and it is inhibited by low concentrations of vanadate (10–50 μM) and -SH inhibitors such as PCMB and PCMBS (10 μM); the enzyme appears to be calmodulin insensitive.
- 3.3. Electrophoretic analyses of plasma membrane proteins demonstrate that: (a) Ca2+ at n-μM concentrations is necessary to activate ATP hydrolysis with consequent formation of the enzyme-phosphate complex; (b) the steady state concentration of the phosphorylated intermediate is increased in the presence of La3+; (c) the mol. wt of Ca2+ ATPase is about 140 kDa.
- 4.4. Low Ca2+ concentrations (n-μM) are sufficient to stimulate the ATP-dependent Ca2+ uptake by plasma membrane inside-out vesicles.
- 5.5. The results indicate that the Ca2+ pump present in the gill plasma membranes could be responsible for Ca2+ extrusion and therefore involved in maintaining the cytosolic Ca2+ concentration within physiological levels.
8.
《The International journal of biochemistry》1984,16(12):1391-1394
- 1.1. Heparin stimulates the activity of nonactivated and activated skeletal muscle phosphorylase kinase in a Ca2+-dependent manner.
- 2.2. The stimulatory effect of heparin on the activity of nonactivated phosphorylase kinase is also expressed in the presence of calmodulin and glycogen. Heparin acted in synergism with glycogen.
- 3.3. Heparin increases the affinity of phosphorylase kinase to Ca2+ 5–12 fold depending upon the activation conditions.
- 4.4. Ca2+ influences the stimulation of liver phosphorylase kinase by heparin in a similar way.
9.
《The International journal of biochemistry》1993,25(5):641-652
- 1.1. A subcellular fractionation procedure for bovine adrenal glands was designed with the aim to study the biochemical properties of Ca2+ stores in chromaffin cells.
- 2.2. The thapsigargin-sensitive compartment of Ca2+ stores was found to be highly enriched in a light microsomal fraction (LMF) on a 15–30% linear sucrose gradient, and was found to be essentially devoid of contamination by plasma, mitochondrial or secretory granule membranes.
- 3.3. A Ca2+-pumping ATPase was identified in this LMF as a 97 kDa protein forming an acid-stable, Ca2+-dependent, thapsigargin-sensitive phosphorylated intermediate upon incubation with [γ-32P]ATP, suggesting this protein to represent a SERCA-3 isoform of Ca2+ ATPases.
- 4.4. A major 162 kDa protein, previously demonstrated in the isolated chromaffin cells, was enriched in the LMF, distributing on sucrose gradients in parallel with the thapsigargin-sensitive Ca2+ uptake.
- 5.5. LMF appears to represent a part of the thapsigargin-sensitive Ca2+ store of chromaffin cells, and should be useful for further studies of the store properties at the subcellular and molecular level.
10.
《The International journal of biochemistry》1991,23(9):881-887
- 1.1. As reported previously (Hopper and Robinson, 1990; Int. J. Biochem. 22, 1165–1170) the sea urchin extraembryonic coat protein hyalin undergoes a Ca2+-induced self-association into an insoluble gel (gelation) in the presence of Mg2+ and/or NaCl.
- 2.2. A 275 kDa peptide fragment, generated by limited tryptic digestion of hyalin, binds Ca2++ but does not undergo gelation in the presence of Ca2+, Mg2+ and NaCl.
- 3.3. Comparisons between the capacities of hyalin and the 275 kDa peptide fragment to bind Ca2+ indicate that the latter binds 88% less Ca2+ than hyalin.
- 4.4. However, the presence of Ca2+ alone, at a concentration of 5 mM, protects the 275 kDa peptide fragment from further digestion by trypsin mimicking the effect of this cation in protecting hyalin.
- 5.5. Gel exclusion Chromatographie analyses of the 275 kDa peptide fragment, both in the presence and absence of 5 mM Ca2+, indicate that this cation does induce self-association of the fragment.
- 6.6. These results provide information on the organization of the functional domains on hyalin which are required for gel formation.
11.
《Comparative biochemistry and physiology. B, Comparative biochemistry》1993,104(3):719-728
- 1.1. Two components of Ca2+-Mg2+-ATPase are observed in kidneys of G. mirabilis. The high-affinity component has a K0.5Ca of 0.23μM; the low-affinity activity K0.5Ca is 90–110μM. The high-affinity activity requires Mg2+, displays Michaelis-Menten kinetics, has peak activity at 1.2 μM Ca2+, and is insensitive to ouabain and Na+ azide.
- 2.2. In subcellular fractions, the high-affinity component segregates with Na+-K+-ATPase and is localized predominantly in BLM. The low-affinity component is broadly distributed among membranous organelles, including brush border, and may be equivalent to alkaline phosphatase.
- 3.3. Specific activity of the high-affinity Ca2+-Mg2+-ATPase is modestly increased following adaptation of fish to FW, but total renal high-affinity activity is greatest in the hypertrophied kidneys of FW-adapted fish and is least in kidneys of fish adapted to 200% SW.
- 4.4. High-affinity Ca2+-Mg2+-ATPase may be associated with active Ca2+ transport or with regulation of intracellular Ca2+ concentration of tubular cells.
12.
《The International journal of biochemistry》1990,22(4):329-333
- 1.1. Ca2+ uptake, Ca2+-dependent ATPase activity and halothane-induced Ca2+ release from the heavy sarcoplasmic reticulum fraction of muscle from malignant hyperthermia susceptible individuals are similar to those of normal human muscle.
- 2.2. Ca2+-induced Ca2+ release from the diseased muscle was increased by 13%.
13.
《Comparative Biochemistry and Physiology》1982,17(1):75-86
- 1.1. Vesicles from the sarcoplasmic reticulum of lobster muscle accumulate Ca2+ if supplied with ATP as an energy source. A search was undertaken for inhibitors of Ca2+ transport.
- 2.2. p-Hydroxymercuribenzoate can completely inhibit Ca2+ transport and ATP hydrolysis. 2–4 Dinitrophenol inhibits uptake but not hydrolysis.
- 3.3. Sr2+, Ba2+ and Zn2+ inhibit uptake, perhaps by competing with Ca2+ for a carrier.
- 4.4. The vesicles contain acetylcholinesterase. Anticholinesterases can reduce —but not abolish—Ca2+ uptake. Acetylcholine has no effect on the activity of the vesicles.
- 5.5. Ca2+ uptake is not affected by Mn2+, glutamate, pilocarpine, carnosine, caffeine, strophanthidin or tetraethylammonium.
- 6.6. K+ is needed for maximal activity of the uptake system but not for ATP hydrolysis. Apparently K+ enhances the coupling between the energy supply and the carrier mechanism.
14.
- 1.1. Ion dependence and vanadium-induced inhibition on branchial sac ATPase in five species of ascidian Phlebobranchiata (vanadium-accumulating) and Stolidobranchiata (iron-accumulating) were studied.
- 2.2. The ATPase was obtained from the microsomal fraction, which was prepared from each ascidian branchial sac.
- 3.3. The ATPase was dependent on Mg2+ and activated by exogenous Na+ + K+.
- 4.4. Ouabain inhibited the ATPase activity in vitro, 10 μM to 100 μM vanadate, in vitro, suppressed the (Na+, K+)-ATPase.
15.
《The International journal of biochemistry》1992,24(10):1633-1638
- 1.1. The activation energy of the membrane bound H+-pyrophosphatase is 44.9 k J·mol−1, for the detergent solubilized enzyme is 55.9 kJ·mol−1.
- 2.2. The Arrhenius plots obtained for pyrophosphatases of Rhodospirillum rubrum show no breaks.
- 3.3. At 70°C, the membrane-bound pyrophosphatase is more stable in the presence of either Mg2+ or Zn2+ than in their absence.
- 4.4. At 65°C, an activator effect of Mg2+ or Zn2+ was observed. Nevertheless, at 70°C no activation was obtained.
- 5.5. The activator effects of Mg2+ or Zn2+ were depended of their concentration.
16.
《The International journal of biochemistry》1990,22(10):1165-1170
- 1.1. As reported previously (Robinson, 1988) the Ca2+-induced self-association reaction of the protein hyalin, purified from the sea urchin extraembryonic hyaline layer, was modulated by both Mg2+ and NaCl.
- 2.2. In the presence of 400 mM NaCl the apparent dissociation constant (Ca2+) decreased five-fold from 4.8 ± 1.1 mM in the absence to 0.9 ± 0.5 mM in the presence of 20 mM Mg2+.
- 3.3. The potentiating effect of Mg2+ occurred with an apparent dissociation constant (Mg2+) of 4.6 ± 0.5mM.
- 4.4. In the absence of Ca2+ or NaCl hyalin dissociated from isolated hyaline layers indicating that the behavior of hyalin within the layer is predictable from results obtained with the purified protein.
17.
《Comparative biochemistry and physiology. A, Comparative physiology》1993,104(3):557-560
- 1.1. Release of creatine kinase (CK) in the Ca2+ paradox of the Langendorff-perfused rat heart is dependent on the conditions of Ca2+ depletion and Ca2+ repletion.
- 2.2. CK release is reduced by raising [Ca2+]o during Ca2+ depletion and progressively increased by extending the Ca2+ free period from 2 to 5 min.
- 3.3. CK release is reduced by decreasing the electrochemical gradient for Ca2+ during Ca2+ repletion.
- 4.4. The findings are discussed in the light of current hypotheses for the biochemical mechanisms that underlie the Ca2+ paradox.
18.
《The International journal of biochemistry》1987,19(10):945-948
- 1.1. The purpose of this study was to determine whether biochemical changes of skeletal muscle that occur as a result of exercise in young rats persist into adulthood.
- 2.2. Littermates (10 days old) were assigned to a 3, 6 and 12 week control or training group. In addition, a rest-exercise group (R-E) and exercise-rest (E-R) group were included.
- 3.3. The rest-exercise and exercise-rest rats were maintained for the 12 weeks with the first 6 weeks being either rest or exercise and the condition reversed during the last 6 weeks of the experiment.
- 4.4. Myofibril ATPase activity of rat plantaris increased from the 10d to 12 week animals (P < 0.05). As anticipated, training resulted in a lowered activity at 6 and 12 weeks compared to controls.
- 5.5. The Ca2+ uptake and Ca2+-ATPase activity of the sarcoplasmic reticulum followed a similar pattern.
- 6.6. With regard to the exercise-rest rats, the myofibril and SR ATPase activities at 12 weeks were comparable to the 12 weeks control rats.
- 7.7. The rest-exercise group approximated the 12 week training group with regard to myofibril and SR ATPase activities (P > 0.05).
- 8.8. The results suggest that the training adaptations that occur during development of skeletal muscle return to normal, when training ceases in the adult rat.
- 9.9. Furthermore, animals that started to train prior to puberty do not have a greater capacity to adapt than animals which initiated training during adulthood.
19.
《Comparative biochemistry and physiology. B, Comparative biochemistry》1993,104(3):547-550
- 1.1. Crude extract of the whole digestive tract from the brown shrimp (P. californiensis) was investigated for digestive amylase activity.
- 2.2. Considerable amylase activity was found at pH 6.5–8.0, with optimum pH at around 7.5.
- 3.3. Optimum temperature was found between 30–40°C, similar to amylases from other crustaceans.
- 4.4. Amylase activity was highly halotolerant, having 50% maximum activity at 3 M NaCl.
- 5.5. Maximum amylase activity was found at 0.01 M NaCl.
- 6.6. Amylase activity was partially inhibited by the divalent ions Hg2+, Zn2+, Cu2+ and Cr2+.
- 7.7. Mg2+ and Ca2+ ions seemed to enhance amylase activity.
20.
- 1.1. Goldfish were kept in deionized water (DW), DW + Na+ (0.35 mM), DW + K+ (0.05 mM), DW + Ca2+ (2mM) and DW + Mg2+ (0.2 mM). In Ca-free environments, prolactin cells appear unaffected. Stimulated calcium-sensitive cells (pars intermedia) may elaborate a hypercalcemic factor.
- 2.2. Fecal excretion, reduced in all groups, remains noticeable in DW + Ca2+
- 3.3. Ionic losses, very low in all groups, are minimal in DW. Supplementation with K+ increases Na+ loss.
- 4.4. Plasma Na+ Ca2+, and osmolarity decrease in DW, and still more in DW + K+. Ca2+' and Mg2+ partly suppress hyponatremia.
- 5.5. In goldfish kept in DW and subsequently in DW + Ca2+, calcemia increases.