Properties Of ATPase Activity Research Articles

Characterization of ATPase activity of class II chaperonin from the hyperthermophilic archaeon Pyrococcus furiosus

To understand how molecular damage under harsh environmental conditions can be controlled, we investigated the properties of ATPase activity of the chaperonin molecular machinery from the hyperthermophilic archaeon Pyrococcus furiosus (PfCPN). PfCPN ATPase activity depended on K(+) and Mg(2+) and its optimal pH was 7.5. PfCPN had almost no ADPase activity. ADP strongly competitively inhibited PfCPN ATPase activity. Inhibition of PfCPN ATPase decreased its chaperonin activity in protecting lysozyme from heat-induced inactivation.

Properties of ATPase activity associated with cell wall fractions from higher plants

Summary Cell wall fractions were prepared from Cucumis hypocotyls and Ricinus cotyledons by low speed centrifugation and repeated washing. The fractions contained ATPase activity that is dependent on Mg2+, stimulated by KCl and strongly inhibited by vanadate and erythrosin B. Some inhibition was observed by azide but this was removed after washing with KI. The results suggest that the ATPase activity associated with the cell wall fractions is predominantly of plasma membrane origin.

Characterization of ATPase activity in the mycelial form cells of yeast Saccharomycopsis fibuligera

1. 1. The properties of ATPase activity were studied with the mycelial form cells of Saccharomycopsis fibuligera. 2. 2. Optimal pH for the activity was about 9.5. 3. 3. The activity was stimulated by Mg 2+. 4. 4. The activity was inhibited by DCCD, NaF and oligomycin, but not inhibited by ouabain.

Characterization of a Light-modulated ATPase Activity in a Microsomal Fraction from Cucumber Hypocotyls

The properties of ATPase activity in a microsomal fraction from etiolated hypocotyls of Cucumis sativus L. were investigated. The ATPase required Mg 2+ , was stimulated by K + and was partially inhibited by vanadate. The effect of K + was unspecific and suggested that, at the tested concentration (50 mM), K + stimulated ATPase activity by facilitating H + extrusion by the ATPase and in turn its further activity. This assumption was supported by the effect of the K + and pH gradients on K + stimulation. The stimulation by K + was increased by red light treatments, while red irradiation in vivo followed by far red irradiation in vitro was less stimulatory. This implies that phytochrome modulates the K + stimulation. Ionophores such as gramicidin and nigericin also stimulated the ATPase activity in the presence of K + . This effect was prominent only after far red irradiation in vitro .

Some properties of ATPase activity in the intact cells of yeast Saccharomycopsis fibuligera

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 Mg 2+. 4. 4. The activity was inhibited by NaF, DCCD, oligomycin, NaN 3, NaVO 3, or PCMB but not inhibited by ouabain.

Properties of ATPase activity in intact vegetative cells and sporulating cells of yeast Saccharomyces cerevisiae

1. 1. The properties of ATPase activity were examined in the intact cells of yeast. 2. 2. The activity was stimulated by Mg 2+, Mn 2+ and Co 2+. 3. 3. The activity was inhibited by NaN 3 and by high concentrations of NaF, NaVO 3 and PCMB. 4. 4. Optimal pH for the activity was approximately 8. 5. 5. The maximum value of the activity was obtained in the cells at the early stationary phase and it decreased in 3 hr after transfer to sporulation medium.

Localization and properties of ATPase activity in pea stems and wheat coleoptiles.

Microsomal fractions from wheat coleoptiles and pea stems contain a microsomal ATPase activity that requires divalent cations (Ca2+ is more effective than Mg2+) and shows further stimulation by KCl. The effects of added indoleacetic acid were inconclusive. Cytochemical studies on both species showed most pronounced staining for ATPase in the plasmalemma at pH 7.0. However, at pH 5.5, the coleoptile cells showed heaviest staining for ATPase in the endoplasmic reticulum and dictyosomes. The results are discussed with regard to the postulated role of ATPase activity in relation to proton pumping and plant cell elongation.

Properties of ATPase activity in coupling factor from Chromatium strain D chromatophores.

Coupling factor extracted from chromatophores of the photosynthetic bacteria Chromatium strain D was partially purified. The enzyme catalyzed ATPase activity in the presence of Ca2+ and Mg2+ ions. Higher Vapp values were obtained when the activity was measured as a function of the divalent cation-ATP complex rather than as a function of either the divalent cation or ATP because the free components competitively inhibited the activity in the presence of the cation-ATP complex. The Km values were lower than or equal to the Ki values for free ATP indicating that the cation-ATP complex is bound tighter than the free ATP to the enzyme. Based on these results a possible mode of binding of substrate to the active site of the enzyme was suggested. A comparative study indicated no changes in the temperature dependance of ATPase activity when the enzyme was solubilized. However, possible conformation changes could have caused a decrease in the Km values for the (Ca-ATP)2- and (Mg-ATP)2- and in the Ki for free Mg2+ ions and ATP. The Ki for free Ca2+ ions increased on solubilization of the coupling factor. ATPase activity was inhibited by dicyclohexylcarbodiimide both in the soluble and in the membrane-bound coupling factor.

魚類筋肉構成たんぱく質に関する研究-IX

A fundamental study on quantitative extraction of actomyosin from frozen ‘surimi’ (fish paste) was made. A determination was achieved by measuring Ca2+-ATPase specific activity and protein content after exhaustively extracting actomyosin from frozen surimi. The quantitative method finally used was as follows: 10g of mined frozen surimi was washed twice with cold 0.05 μ phosphate buffer, pH 7.5. The residue was then homogenized for 3min in 30ml of cold 0.8 M KCI, pH 7.0 at about 6, 000 rpm by homogenizer (Nihon Seiki K. K. type HB). Extraction was carried out for 2 hr after washing out homogenate by adding another 20ml of cold 0.8 M KCI, pH 7.0. Extracted protein was collected by centrifugation at 7, 000×g for 20 min and diluted by the addition of 10 volumes of cold water. The precipitated protein was collected, dissolved into 0.6 M KCI, pH 6.8, and dialyzed against the same solution. The precipitated protein which separated by centrifugation at 15, 000×g for 60min, was redissolved into 0.6 M KCI, pH 6.8 by grinding up with a magnetic stirrer (‘precipitated protein’ fraction). The content of protein and Ca2+-ATPase specific activity in the supernatant and precipitated protein fractions were measured and the amount of actomyosin in frozen surimi could be determined as the sum of Ca2+-ATPase total activity (μ moles Pi liberated/min/10g of surimi) in both fractions. It was suggested that the precipitated protein fraction could contain denatured forms (modified molecules) of actomyosin, since the properties of ATPase activity in the fraction were very similar to those of native actomyosin.

Distribution and properties of ATPase activities in the cochlea of the chicken

1. 1. The properties and distribution of an ouabain sensitive Na +-K +-ATPase system in the cochlear structures of the chicken were investigated with ultramicrochemical techniques. 2. 2. The properties of this enzyme system are in good agreement with those found in other tissues including the stria vascularis. 3. 3. The enzyme system was present in very high activity and appeared to be predominantly located in the tegmentum vasculosum. 4. 4. The agreement between the activities and properties of the Na +-K +-ATPase system in the tegmentum vasculosum of the chicken cochlea and the stria vascularis of the mammalian cochlea suggests that the tegmentum vasculosum may play the same essential role in the maintenance of the cochlear cation gradients and the cochlear potentials as the stria vascularis.

Properties of ATP-ase activities of membrane fractions from the sheath of squid giant axons

Properties of ATP-ase activities of membrane fractions from the sheath of squid giant axons