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1.
《The International journal of biochemistry》1993,25(12):1963-1968
- 1.1. The native rat-kidney cortex Fructose-1,6-BPase is differentially regulated by Mg2+ and Mn2+.
- 2.2. Mg2+ binding to the enzyme is hyperbolic and large concentrations of the cation are non-inhibitory.
- 3.3. Mn2+ produces a 10-fold rise in Vmax higher than Mg2+. [Mn2+]0.5 is much larger than [Mg2+]0.5. At elevated [Mn2+] inhibition is observed.
- 4.4. Mg2+ and Mn2+ produce antagonistic effects on the inhibition of the enzyme by high substrate.
- 5.5. Fru-2,6-P2 inhibits the enzyme by rising the S0.5 and favouring a sigmoidal kinetics.
- 6.6. The inhibition by Fru-2,6-P2 is released by Mg2+ and more powerfully by Mn2+ increasing the I0.5.
2.
《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.
3.
《Comparative biochemistry and physiology. B, Comparative biochemistry》1989,92(3):487-492
- 1.1. Subcellular distribution of (NA+, K+-ATPase and ouabain-insensitive ATPase (Mg2+-ATPase) are compared in branchial tissues of the euryhaline crab, Eriocheir sinensis, acclimated to fresh water.
- 2.2. Both the anterior and posterior gills contain cAMP-dependent protein kinase and endogenous protein substrate for phosphorylation.
- 3.3. Phosphorylation occurs in both “particulate” and “soluble” subcellular fractions but its stimulation by cAMP is restricted to the “soluble” fraction.
- 4.4. serotonin (5-HT) and dopamine receptors are present only in the “light particulate” fraction isolated from the posterior gills.
- 1.(a) Serotonin and dopamine have no effect on the phosphorylation observed in a subcellular fraction alone.
- 2.(b) Activation of the phosphorylation by serotonin and dopamine is found when the soluble fraction (source of cAMP-dependent protein kinase) is added to the fraction P3 from the posterior gills.
- 3.(c) No activation occurs with the fractions P3 as well as P1 or P2 (not shown) from anterior gills of fresh water crab.
- 4.(d) Cyproheptadine, a serotonin receptor antagonist, inhibits the 5-HT dependent increase in phosphorylation.
- 5.(e) The dopamine receptor antagonist, chlorpromazine, inhibits dopamine-stimulated phosphorylation.
- 6.5. Ouabain mimics the effect of cyproheptadine on the serotonin-stimulated phosphorylation found in the posterior gills.
4.
《Comparative biochemistry and physiology. A, Comparative physiology》1992,101(1):113-118
- 1.1. The effects of pressure on synaptic currents were examined in crayfish abdominal muscles.
- 2.2. Helium pressure (10.1 MPa) considerably decreased extracellulariy-recorded excitatory junctional potentials associated with increased short-term facilitation.
- 3.3. These effects could be mimicked by a reduction of [Ca2+]o, and partially compensated by an increase in [Ca2+]o.
- 4.4. Pressure also reduced the amplitude of the extracellular nerve terminal potentials (ENTP) by up to 25%, and significantly increased synaptic delay in a [Ca2+]o-dependent manner.
- 5.5. The interaction between compression and various [Ca2+]o were analysed in terms of an existing model of transmitter release. The results were consistent with the hypothesis that high pressure decreases the maximal Ca2+ influx into nerve terminals.
- 6.6. The decreased ENTP and increased synaptic delay suggest that additional processes may be involved in pressure effects on synaptic transmission.
5.
《The International journal of biochemistry》1993,25(8):1109-1114
- 1.1. The regulation of the increase in the cytosolic calcium concentration ([Ca2+]c) induced by extracellular ATP in AS-30D hepatoma cells was studied.
- 2.2. Homologous desensitization involving the refilling of intracellular calcium pools and the participation of protein kinase C was found.
- 3.3. Isoproterenol, forskolin and dibutyril-cyclic AMP also induced an increase in [Ca2+]c.
- 4.4. Interestingly, synergism was found for isoproterenol or forskolin and ATP.
- 5.5. The results suggest that there are two pathways for mobilizing [Ca2+] in AS-30D hepatoma cells; one is activated by ATP receptors and the other by cyclic AMP.
6.
《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.
7.
《Comparative biochemistry and physiology. B, Comparative biochemistry》1993,104(3):563-573
- 1.1. Glossina morsitans morsitans (Gmm), G. palpalis gambiensis (Gpg) and G. tachinoides (Gt) haemolymph possessed multiple, glycoproteinaceous haemagglutinins (HGN).
- 2.2. Tsetse HGN bind to human erythrocyte surface glycoprotein/glycopeptide residues or, with Gmm and Gpg anti-0 activity, glycolipid moieties.
- 3.3. Variations in HGN physico-chemical properties occurred between the morsitans (Gmm) and palpalis (Gpg and Gt), and amongst the palpalis, groups of flies with respect to relative heat-lability, susceptibility to dithiothreitol reduction, resistance to γ-radiation exposure and sensitivity to urea treatment.
- 4.4. Gt and Gmm required acid and acid to neutral conditions respectively, and Ca2+ ion presence, for optimum agglutination activity whilst Gpg required neutral to alkaline pH and Mg2+ ions.
- 5.5. The findings reported here provide further information regarding HGN (lectin) properties in different species of the genus Glossina, member of the Diptera, a little studied order with respect to insect vector immunity.
8.
《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.
9.
《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.
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.
《The International journal of biochemistry》1993,25(8):1183-1187
- 1.1. Synaptic plasma membrane vesicles (SPMV) from rat brain synthesized ceramide-phosphoethanolamine (SpE), an analogue of sphingomyelin (SpC) from phosphatidylethanolamine (PE) and ceramide.
- 2.2. This reaction was catalyzed by PE: ceramide-phosphotransferase.
- 3.3. The presence of PC did not modify the SpE synthesis and PI and PS at twice PE concentration seemed to be activators; only PG was an inhibitor at all concentrations.
- 4.4. Some cations (Mg2+, Mn2+) were without effect, while Ca2+ increased transferase activity, so was interesting to study.
- 5.5. Transferase was compared with sialidase (external enzyme).
- 6.6. Kinetics other than those already performed by us were undertaken in order to confirm its location.
12.
《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.
13.
《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.
14.
《Comparative biochemistry and physiology. B, Comparative biochemistry》1987,86(3):855-862
- 1.1. A method for purifying undischarged nematocysts from Hydra and other cnidarians is described.
- 2.2. Isolated cysts (relative densities 1.22–1.24) evaginate their tubular content even after previous dehydration.
- 3.3. The cyst wall is permeable to dyes of mol. wts up to 600,000.
- 4.4. Approximately two-thirds of the cyst's dry wt are soluble proteins. Eighty per cent of them are of low mol. wt and highly anionic, presumably serving as binding sites for Ca2+ and Mg2+.
- 5.5. The other 20% includes 30 different proteins amongst them toxins and enzymes (phospholipase and little proteases but no collagenase, chitinase or hyaluronidase).
15.
《Comparative biochemistry and physiology. A, Comparative physiology》1987,86(3):563-570
- 1.1. The study was carried out on 22 species of insects from 5 orders. The osmolality of their hemolymph varied from 319 to 421 mOsm/kg H2O, concentration of Na+ 4.6 to 118 mM/l, K+ 6.3 to 73mM/l, Ca2+ 3.6 to 12.9 mM/l, Mg2+ 2.3 to 76 mM/l. The most abundant cation in the hemolymph of insects from higher orders is either K+ or Mg2+.
- 2.2. In the muscles of lower and higher insects K+ is usually within 80–120 mM/kg wet wt.
- 3.3. Most Ca2+ and Mg2+ in hemolymph is bound with protein and low molecular anions, concentration of free Ca2+ is 0.9-2.1mM/l Mg2+ 3.7–8.0 mM/l.
- 4.4. It is concluded that, in insects, potassium hemolymph, cell volume regulation and accumulation of ions in the cell, are ensured by an increased osmolality of hemolymph due to a high percentage contribution of low molecular organic substances which are retained in the hemolymph due to the absence of filtration apparatus in the Malpighian tubules.
16.
《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.
17.
- 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.
18.
《The International journal of biochemistry》1986,18(7):589-594
- 1.1. The properties of ATPase activity were studied with the cells at the early stationary phase of Saccharomycopsis fibuligera.
- 2.2. Optimal pH for the activity was approximately 7.
- 3.3. The activity was stimulated by Mg2+.
- 4.4. The activity was inhibited by NaF, DCCD, oligomycin, NaN3, NaVO3, or PCMB but not inhibited by ouabain.
19.
《Comparative biochemistry and physiology. A, Comparative physiology》1993,104(4):621-626
- 1.1. Eyestalk unablated and unilaterally ablated Penaeus monodon juveniles had survival rates after 5 months of 75–72.5 and 67.5–60%, respectively.
- 2.2. Unilaterally ablated shrimps had significantly higher (P < 0.05) growth rate than unablated shrimps.
- 3.3. Eyestalk-ablatement resulted in a decrease in the haemolymph sodium concentration and an increase in the potassium and calcium concentration of shrimps.
- 4.4. The osmolarity of haemolymph and total protein concentration of unablated shrimps were demonstrated to be higher than those of unilaterally ablated shrimps.
- 5.5. The eyestalk-ablated shrimps possess higher total ATPase and Na+,K+-ATPase activities in the gill than those of unablated shrimps.
20.
《The International journal of biochemistry》1993,25(12):1969-1974
- 1.1. The native rat-kidney cortex Fructose-1,6-bisphosphatase is differentially regulated by adenine nucleotides in the presence of divalent cations.
- 2.2. Binding of AMP and ADP to the enzyme is co-operative. The inhibition by both nucleotides show an uncompetitive mechanism AMP being the most efficient inhibitor.
- 3.3. Mg2+ decreases the inhibition produced by AMP and ADP by enhancing their I0.5 and completely annulates the inhibitory effect of ATP.
- 4.4. In the presence of Mn2+ ADP behaves as an inhibitor but no inhibition is evident with AMP, suggesting the existence of different allosteric sites for each nucleotide.