Relationship of potassium ion transport and ATP synthesis in pea cotyledon mitochondria

1977 ◽  
Vol 55 (4) ◽  
pp. 376-383
Author(s):  
W. M. Hamman ◽  
Mary Spencer
Keyword(s):  
Atp Synthesis ◽  
Inhibitory Effect ◽  
Potassium Ion ◽  
Magnesium Ions ◽  
Mitochondrial Membranes ◽  
Reasonable Time ◽  
Potassium Ion Transport ◽  
Potassium Ion Uptake ◽  
Relationship Of ◽  
External K

Simultaneous monitoring of ATP synthesis and K+ movements across pea mitochondrial membranes revealed information about the competition of the two processes for mitochondrial energy. In the presence of valinomycin and at low extramitochondrial K+ concentration, ADP could be phosphorylated rapidly. This occurred with a decrease in net potassium ion uptake. At higher external K+ concentrations respiratory energy was unavailable for ATP synthesis and only a portion of added ADP could be phosphorylated within a reasonable time. Magnesium ions were shown to have an inhibitory effect on the K+ uptake, and stimulated a greater rate of ATP synthesis. When valinomycin and ADP were added simultaneously so that phosphorylation of the ADP and enhancement of K+ uptake could compete for mitochondrial energy, K+ uptake was preferred over ATP synthesis.

scholarly journals New Enzymatic Assay with Urea Amidolyase for Determining Potassium in Serum

1997 ◽  
Vol 34 (4) ◽  
pp. 384-388 ◽  
Author(s):  
Shigeki Kimura ◽  
Shigeru Iyama ◽  
Yoshihisa Yamaguchi ◽  
Sadao Hayashi ◽  
Ryo Fushimi ◽  
...  
Keyword(s):  
Calcium Ion ◽  
Inhibitory Effect ◽  
Potassium Ion ◽  
Ion Concentration ◽  
Ammonium Ion ◽  
Magnesium Ions ◽  
Tetraacetic Acid ◽  
Selective Electrode ◽  
Coefficients Of Variation ◽  
Analytical Recovery

We developed a new simple assay for potassium ion in serum using urea amidolyase (UAL) from yeast sp. The method is based on activation of the enzyme by potassium ion. We eliminated endogenous ammonium ion by use of glutamate dehydrogenase (GLDH), and then monitored the production of ammonium ion by UAL, urea, ATP, bicarbonate and magnesium ions. Ammonium ion was produced proportional to the potassium ion concentration and was determined by adding GLDH to produce NADP+ in the presence of 2-oxoglutarate and NADPH. We monitored the change of absorbance at 340 nm. The inhibitory effect of calcium ion to this assay was eliminated by adding glycoletherdiamine-N, N, N', N'-tetraacetic acid to the reaction. The within-assay coefficients of variation (CV) of this method were 0·99–1·55% ( n = 10) at 3·32–6·18mmol/L. Day-to-day CVs ranged from 1·49% to 2·46%. The analytical recovery was 96–108%. The correlation coefficient between the values obtained by our method ( y) and those by the ion-selective electrode (ISE) method ( x) was 0·994 ( y = 1·032x-0·166 mmol/L, S y·x = 0·110, n = 100). The presence of bilirubin, haemoglobin or other ions did not affect this assay, confirming the usefulness of this assay for clinical purposes.

Potassium Ion Transport by Valinomycin across a Hg-Supported Lipid Bilayer

2005 ◽  
Vol 127 (38) ◽  
pp. 13316-13323 ◽  
Author(s):  
Lucia Becucci ◽  
Maria Rosa Moncelli ◽  
Renate Naumann ◽  
Rolando Guidelli
Keyword(s):  
Ion Transport ◽  
Lipid Bilayer ◽  
Potassium Ion ◽  
Supported Lipid Bilayer ◽  
Potassium Ion Transport

A Study on the Influence of Cysteine and Magnesium Ions on Brain Dementia

2014 ◽  
Vol 487 ◽  
pp. 161-164
Author(s):  
Lu Yin ◽  
Shuang Yue Zhu
Keyword(s):  
Vascular Dementia ◽  
Plasma Homocysteine ◽  
Diagnosis And Treatment ◽  
Magnesium Ion ◽  
Disease Development ◽  
Mechanism Analysis ◽  
Magnesium Ions ◽  
Patients Âgés ◽  
Dementia Patients ◽  
Relationship Of

As the population ages, dementia disease is increasingly becoming the most concerned social problems. According to the cause of dementia, it can be divided into many kinds class, among them with Alzheimer's Disease (Alzheimers diseases, AD) and Vascular Dementia (Vascular Dementia, VD) are common. Data shows it accounts for nearly 60% of total AD dementia patients, VD (20%), but only 2% of patients could get timely diagnosis and treatment, make its cognitive damage to a certain extent suppress and improve. for untimely diagnosis and treatment, most patients makes the disease development worse. In recent years, studies have shown that plasma Homocysteine,Hcy levels associated with AD. And studies show that from the power of the risk factors to the mechanism analysis, dementia disease level correlation with magnesium ions. On this basis, this study of plasma homocysteine in patients with AD,VD and magnesium ion detection results were analyzed retrospectively. Discuss their levels between the distributio relationship of patients ages in AD and VD.

KCNQ5 Participates in Form Deprivation Myopia by Regulating Potassium Ion Transport Pathway

2021 ◽  
Author(s):  
Qin Yang ◽  
Qingqing Tan ◽  
Changjun Lan ◽  
Bozhen Lv ◽  
Guimei Zhou ◽  
...  
Keyword(s):  
Ion Transport ◽  
Potassium Ion ◽  
Transport Pathway ◽  
Potassium Ion Transport

Functions of selected biochemical systems from the exercised-trained dog heart

1977 ◽  
Vol 42 (3) ◽  
pp. 426-431 ◽  
Author(s):  
L. A. Sordahl ◽  
G. K. Asimakis ◽  
R. T. Dowell ◽  
H. L. Stone
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Calcium Transport ◽  
Calcium Uptake ◽  
Atp Synthesis ◽  
Myocardial Cell ◽  
Ruthenium Red ◽  
Mitochondrial Membranes ◽  
Sedentary Control ◽  
Isolated Mitochondria ◽  
Biochemical Systems

Mitochondria and sarcoplasmic reticulum (SR) fractions were isolated from exercised-trained (E-T) and sedentary control dog hearts. Measurements of mitochondrial respiratory functions indicated no changes in energy-producing (ATP synthesis) capacity in mitochondria from E-T compared to control dog hearts. However, the ability of isolated mitochondria from E-T hearts to retain accumulated calcium was markedly decreased compared to controls. Inhibition of mitochondrial rates of calcium uptake with the inhibitor, ruthenium red, revealed fewer binding and/or transport sites in mitochondrial membranes from exercised-trained heart preparations. ATP-dependent binding (- oxalate) and uptake (+ oxalate) of calcium by SR preparations from E-T hearts were unchanged compared to controls. In contrast, significant differences in the rates of release of bound calcium were found in SR isolated from E-T hearts. Total myocardial protein, nucleic acids, and connective tissue levels were unchanged in E-T hearts compared to controls. The results suggest subtle changes are occurring in the energy-utilizing mechanism(s) involving calcium transport of the myocardial cell during exercise training. These changes may be related to alterations in the performance of the exercised-trained heart.

Charakterisierung und Kinetik des in der Rattenplacenta vorkommenden mikrosomalen Enzyms, das den Wasserstoff-Transfer von Oestradiol auf Androstendion katalysiert / Characterization and Kinetics of the Microsomal Enzyme of Rat Placenta which Functions as a “Transhydrogenase” between Estradiol-17β and Androstenedione

1971 ◽  
Vol 26 (7) ◽  
pp. 710-719 ◽  
Author(s):  
Kunhard Pollow ◽  
Barbara Pollow
Keyword(s):  
Hydrogen Transfer ◽  
Microsomal Fraction ◽  
Close Relation ◽  
Inhibitory Effect ◽  
Magnesium Ions ◽  
Michaelis Constant ◽  
Temperature Optimum ◽  
Optimum Ph ◽  
Kinetics Of ◽  
Estradiol 17Β

The microsomal fraction of rat placenta contains a 17β-hydroxysteroid-oxidoreductase which transfers hydrogen from position 17 of estradiol to androstenedione. This hydrogen transfer is dependent on NAD, NADP as cofactor is without effect. The optimum pH is at 6,9. In the presence of NAD the Michaelis constant for estradiol is 4,17 · 10-5м at pH 7,4. In the presence of androstenedione in the incubation medium the Km-value for estradiol is decreased, which indicates an increased affinity for the enzyme. The temperature optimum of the enzyme is 38 °C. Addition of SH-blocking agents inhibited the enzyme activity. Zinc and magnesium ions had an inhibitory effect on the “transhydrogenase” and B-NADPT specifically labelled from [1-T]-glucose showed that the non-effect of NADP on transhydrogenation from estradiol to androstenedione resulting in reduction of position 17 is not due to different stereospecifity.The results show a close relation between the oxidative metabolism of estradiol and the reduction of androstenedione, indicating that estradiol-17β, as the preferred hydrogen-donating substrate, is an essential component of the androstenedione-hydrogenating system in the microsomal fraction of rat placenta.

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