Kinetic studies on rat liver and beef heart mitochondrial adenosine triphosphatase: The effects of the chromium complexes of adenosine triphosphate and adenosine diphosphate on the kinetic properties

1975 ◽  
Vol 171 (2) ◽  
pp. 656-661 ◽  
Author(s):  
Sheldon M. Schuster ◽  
Richard E. Ebel ◽  
Henry A. Lardy
Keyword(s):  
Adenosine Triphosphate ◽  
Rat Liver ◽  
Adenosine Triphosphatase ◽  
Kinetic Studies ◽  
Adenosine Diphosphate ◽  
Kinetic Properties ◽  
Beef Heart ◽  
Chromium Complexes

Studies on the mechanism of action of ethylene. II. Effects of ethylene on mitochondria from rat liver and yeast, and on mitochondrial adenosine triphosphatase

1968 ◽  
Vol 46 (3) ◽  
pp. 283-288 ◽  
Author(s):  
A. O. Olson ◽  
Mary Spencer
Keyword(s):  
Adenosine Triphosphate ◽  
Rat Liver ◽  
Mechanism Of Action ◽  
Mitochondrial Membrane ◽  
Adenosine Triphosphatase ◽  
Adenosine Diphosphate ◽  
Yeast Mitochondria ◽  
Mitochondrial Volume ◽  
High Concentrations

Ethylene treatment of rat liver and yeast mitochondria was found to increase the rate of mitochondrial volume change caused by adenosine diphosphate or adenosine triphosphate. As well, ethylene increased the rate of adenosine triphosphate hydrolysis by mitochondria from rat liver, yeast, and bean cotyledons. However, the gas had no effect on the reactivity of a partially purified adenosine triphosphatase prepared from mitochondria of rat liver or bean cotyledon. For ethylene to exert its effect, it appears that the enzyme must be in its natural locale in the mitochondrial membrane, where the gas can accumulate in relatively high concentrations. The effects of ethylene on respiration in vivo are explicable on the basis of these observations.

Mechanisms of inhibition of adenine phosphoribosyltransferase by adenine nucleosides and nucleotides

1970 ◽  
Vol 48 (5) ◽  
pp. 573-579 ◽  
Author(s):  
J. Frank Henderson ◽  
R. E. A. Gadd ◽  
H. M. Palser ◽  
M. Hori
Keyword(s):  
Adenosine Triphosphate ◽  
Kinetic Studies ◽  
Adenosine Diphosphate ◽  
Free Enzyme ◽  
Adenine Phosphoribosyltransferase ◽  
Enzyme Form

Kinetic studies of the inhibition of adenine phosphoribosyltransferase by adenine 6′-deoxyallofuranoside and 2′-deoxyadenylate indicate that both compounds bind to free enzyme and to the enzyme–phosphoribosylpyrophosphate complex, although they bind with different relative affinities to each enzyme form. The sites to which these inhibitors bind appear to be different from those to which substrates and products bind. Kinetic and physical studies show that adenosine diphosphate and adenosine triphosphate also bind to several enzyme forms, and that their mechanisms of inhibition of this enzyme are complex.

scholarly journals Flexibility of an Active Center in Sodium-Plus-Potassium Adenosine Triphosphatase

1969 ◽  
Vol 54 (1) ◽  
pp. 306-326 ◽  
Author(s):  
R. L. Post ◽  
S. Kume ◽  
T. Tobin ◽  
B. Orcutt ◽  
A. K. Sen
Keyword(s):  
Active Center ◽  
Adenosine Triphosphate ◽  
Adenosine Triphosphatase ◽  
Plasma Membranes ◽  
Adenosine Diphosphate ◽  
Ion Concentration ◽  
Potassium Ions ◽  
Sodium Ions ◽  
Intact Cells ◽  
Electrophoretic Patterns

In plasma membranes of intact cells an enzymatic pump actively transports sodium ions inward and potassium ions outward. In preparations of broken membranes it appears as an adenosine triphosphatase dependent on magnesium, sodium, and potassium ions together. In this adenosine triphosphatase a phosphorylated intermediate is formed from adenosine triphosphate in the presence of sodium ions and is hydrolyzed with the addition of potassium ions. The normal intermediate was not split by adenosine diphosphate. However, selective poisoning by N-ethylmaleimide or partial inhibition by a low magnesium ion concentration yielded an intermediate split by adenosine diphosphate and insensitive to potassium ions. Pulse experiments on the native enzyme supported further a hypothesis of a sequence of phosphorylated forms, the first being made reversibly from adenosine triphosphate in the presence of sodium ion and the second being made irreversiblyfrom the first and hydrolyzed in the presence of potassium ion. The cardioactive steriod inhibitor, ouabain, appeared to combine preferentially with the second form. Phosphorylation was at the same active site according to electrophoretic patterns of proteolytic phosphorylated fragments of both reactive forms. It is concluded that there is a conformational change in the active center for phosphorylation during the normal reaction sequence. This change may be linked to one required theoretically for active translocation of ions across the cell membrane.

scholarly journals The control of isocitrate oxidation by rat liver mitochondria

1969 ◽  
Vol 114 (2) ◽  
pp. 215-225 ◽  
Author(s):  
D. G. Nicholls ◽  
P. B. Garland
Keyword(s):  
Respiratory Chain ◽  
Rat Liver ◽  
Isocitrate Dehydrogenase ◽  
Adenine Nucleotides ◽  
Kinetic Studies ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Kinetic Properties ◽  
Dependent Inhibition ◽  
Nad 4

1. The factors capable of affecting the rate of isocitrate oxidation in intact mitochondria include the rate of isocitrate penetration, the activity of the NAD-specific and NADP-specific isocitrate dehydrogenases, the activity of the transhydrogenase acting from NADPH to NAD+, the rate of NADPH oxidation by the reductive synthesis of glutamate and the activity of the respiratory chain. A quantitative assessment of these factors was made in intact mitochondria. 2. The kinetic properties of the NAD-specific and NADP-specific isocitrate dehydrogenases extracted from rat liver mitochondria were examined. 3. The rate of isocitrate oxidation through the respiratory chain in mitochondria with coupled phosphorylation is approximately equal to the maximal of the NAD-specific isocitrate dehydrogenase but at least ten times as great as the transhydrogenase activity from NADPH to NAD+. 4. It is concluded that the energy-dependent inhibition of isocitrate oxidation by palmitoylcarnitine oxidation is due to an inhibition of the NAD-specific isocitrate dehydrogenase. 5. Kinetic studies of NAD-specific isocitrate dehydrogenase demonstrated that its activity could be inhibited by one or more of the following: an increased reduction of mitochondrial NAD, an increased phosphorylation of mitochondrial adenine nucleotides or a fall in the mitochondrial isocitrate concentration. 6. Uncoupling agents stimulate isocitrate oxidation by an extent equal to the associated stimulation of transhydrogenation from NADPH to NAD+. 7. A technique is described for continuously measuring with a carbon dioxide electrode the synthesis of glutamate from isocitrate and ammonia.

scholarly journals Altered chemomechanical coupling causes impaired motility of the kinesin-4 motors KIF27 and KIF7

2018 ◽  
Vol 217 (4) ◽  
pp. 1319-1334 ◽  
Author(s):  
Yang Yue ◽  
T. Lynne Blasius ◽  
Stephanie Zhang ◽  
Shashank Jariwala ◽  
Benjamin Walker ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Cell Division ◽  
Adenosine Triphosphate ◽  
Adenosine Triphosphatase ◽  
Adenosine Diphosphate ◽  
Microtubule Dynamics ◽  
Microtubule Organization ◽  
High Affinity ◽  
Chemomechanical Coupling ◽  
Mechanistic Basis

Kinesin-4 motors play important roles in cell division, microtubule organization, and signaling. Understanding how motors perform their functions requires an understanding of their mechanochemical and motility properties. We demonstrate that KIF27 can influence microtubule dynamics, suggesting a conserved function in microtubule organization across the kinesin-4 family. However, kinesin-4 motors display dramatically different motility characteristics: KIF4 and KIF21 motors are fast and processive, KIF7 and its Drosophila melanogaster homologue Costal2 (Cos2) are immotile, and KIF27 is slow and processive. Neither KIF7 nor KIF27 can cooperate for fast processive transport when working in teams. The mechanistic basis of immotile KIF7 behavior arises from an inability to release adenosine diphosphate in response to microtubule binding, whereas slow processive KIF27 behavior arises from a slow adenosine triphosphatase rate and a high affinity for both adenosine triphosphate and microtubules. We suggest that evolutionarily selected sequence differences enable immotile KIF7 and Cos2 motors to function not as transporters but as microtubule-based tethers of signaling complexes.

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