A model for intracellular energy transport

1982 ◽  
Vol 60 (1) ◽  
pp. 98-102 ◽  
Author(s):  
G. W. Mainwood ◽  
K. Rakusan
Keyword(s):  
Free Energy ◽  
Creatine Kinase ◽  
Oxygen Transfer ◽  
Energy Transport ◽  
Atp Hydrolysis ◽  
Creatine Phosphate ◽  
Free Cell ◽  
Cell Periphery ◽  
Maximum Work ◽  
Intracellular Energy

A model for oxygen transfer to cells from capillaries is considered in which mitochondria are either clustered at the cell periphery around capillaries or homogeneously distributed through the cytosol. The capillary [Formula: see text] required to supply cells utilizing oxygen at the same rate is much less when mitochondria cluster around capillaries. Two alternative mechanisms are considered for distributing energy from peripheral mitochondria to the rest of the cell; i.e., diffusion of ATP or creatine phosphate with enough creatine kinase to ensure equilibrium between the ~P carriers. The latter has clear advantages and would appear to be adequate to supply a fairly large mitochondria-free cell core (e.g., 24-μm diameter) with very little change in ADP levels or in the free energy of ATP hydrolysis at maximum work rates. Thus, a viable alternative to the traditional Krogh model is presented which takes into account the inhomogeneity of the diffusion pathway as a result of mitochondrial clustering.

Role of creatine phosphokinase in cellular function and metabolism

1978 ◽  
Vol 56 (5) ◽  
pp. 691-706 ◽  
Author(s):  
V. A. Saks ◽  
L. V. Rosenshtraukh ◽  
V. N. Smirnov ◽  
E. I. Chazov
Keyword(s):  
Energy Transport ◽  
Creatine Phosphokinase ◽  
Surface Membrane ◽  
Creatine Phosphate ◽  
Contractile Force ◽  
Energy Utilization ◽  
Regulatory Factor ◽  
Main Attention ◽  
Intracellular Energy

This paper summarizes the data concerning the role of the creatine phosphokinase system in muscle cells with main attention to the cardiac muscle. Creatine phosphokinase isoenzymes play a key role in the intracellular energy transport from mitochondria to myofibrils and other sites of energy utilization. Due to the existence of the creatine phosphate pathway for energy transport, intracellular creatine phosphate concentration is apparently an important regulatory factor for muscle contraction which influences the contractile force by determining the rate of regeneration of ATP directly available for myosin ATPase, and at the same time controls the activator calcium entry into the myoplasm across the surface membrane of the cells.

scholarly journals Molecular docking and density functional theory studies on creatine, guanidinoacetic acid, and their phosphorylated analogues binding to muscle creatine kinase

2020 ◽  
pp. 174751982097858
Author(s):  
M Vraneš ◽  
S Ostojić ◽  
Č Podlipnik ◽  
A Tot
Keyword(s):  
Density Functional Theory ◽  
Creatine Kinase ◽  
Molecular Docking ◽  
Density Functional ◽  
Creatine Phosphate ◽  
Docking Studies ◽  
Muscle Creatine Kinase ◽  
Functional Theory ◽  
Guanidinoacetic Acid ◽  
Muscle Creatine

Comparative molecular docking studies on creatine and guanidinoacetic acid, as well as their phosphorylated analogues, creatine phosphate, and phosphorylated guanidinoacetic acid, are investigated. Docking and density functional theory studies are carried out for muscle creatine kinase. The changes in the geometries of the ligands before and after binding to the enzyme are investigated to explain the better binding of guanidinoacetic acid and phosphorylated guanidinoacetic acid compared to creatine and creatine phosphate.

scholarly journals Relationship between the free energy of ATP hydrolysis and step rotation of F_1-ATPase

2003 ◽  
Vol 43 (supplement) ◽  
pp. S134
Author(s):  
E. Muneyuki ◽  
T. Watanabe ◽  
H. Noji ◽  
T. Nishizaka ◽  
M. Yoshida
Keyword(s):  
Free Energy ◽  
Atp Hydrolysis

scholarly journals Effect of muscle action and metabolic strain on oxidative metabolic responses in human skeletal muscle

1999 ◽  
Vol 87 (5) ◽  
pp. 1768-1775 ◽  
Author(s):  
C. A. Combs ◽  
A. H. Aletras ◽  
R. S. Balaban
Keyword(s):  
Free Energy ◽  
Atp Hydrolysis ◽  
Tibialis Anterior Muscle ◽  
Respiratory Control ◽  
Oxidative Capacity ◽  
Resonance Spectroscopy ◽  
Muscle Action ◽  
Pooled Data ◽  
Muscle Actions

A recent report suggests that differences in aerobic capacity exist between concentric and eccentric muscle action in human muscle (T. W. Ryschon, M. D. Fowler, R. E. Wysong, A. R. Anthony, and R. S. Balaban. J. Appl. Physiol. 83: 867–874, 1997). This study compared oxidative response, in the form of phosphocreatine (PCr) resynthesis rates, with matched levels of metabolic strain (i.e., changes in ADP concentration or the free energy of ATP hydrolysis) in tibialis anterior muscle exercised with either muscle action in vivo ( n = 7 subjects). Exercise was controlled and metabolic strain measured by a dynamometer and 31P-magnetic resonance spectroscopy, respectively. Metabolic strain was varied to bring cytosolic ADP concentration up to 55 μM or decrease the free energy of ATP hydrolysis to −55 kJ/mol with no change in cytoplasmic pH. PCr resynthesis rates after exercise ranged from 31.9 to 462.5 and from 21.4 to 405.4 μmol PCr/s for concentric and eccentric action, respectively. PCr resynthesis rates as a function of metabolic strain were not significantly different between muscle actions ( P > 0.40), suggesting that oxidative capacity is dependent on metabolic strain, not muscle action. Pooled data were found to more closely conform to previous biochemical measurements when a term for increasing oxidative capacity with metabolic strain was added to models of respiratory control.

Tropomyosin-Troponin-Induced Changes in the Partitioning of Free Energy Release of Actomyosin-Catalyzed ATP Hydrolysis as Measured by ATP-Phosphate Exchange

1980 ◽  
Vol 35 (5-6) ◽  
pp. 431-438 ◽  
Author(s):  
Peter Dancker
Keyword(s):  
Free Energy ◽  
Atpase Activity ◽  
Energy Release ◽  
Atp Hydrolysis ◽  
Free Energy Change ◽  
Energy Change ◽  
Experimental Conditions ◽  
Mean Values ◽  
Induced Changes ◽  
Phosphate Exchange

Abstract ATPase activity and ATP-Pi exchange of unregulated (without tropomyosin-troponin) and regulated (with tropomyosin-troponin) acto-HMM were measured in media containing 0.2 mg/ml actin, HMM, and (when present) tropomyosin-troponin, 2 mM MgCl2, 10 m M KCl, 2 mM NaN3, 10 mM Pi(pH 7.0), 3 mM ATP. The following mean values for ATPase activity and for the rate of incorporation of P, into ATP (each per mg HMM and per min) were obtained: unregulated acto-HMM 0.33 nmol Pi and 0.33 nmol Pi, regulated acto-HMM 0.54 nmol Pi and 1.06 nmol P*. The ratio of P4 incorporation rate to ATPase activity was 1.01 × 10-3 for unregulated and 2.02 × 10-3 for regulated acto-HMM. From these ratios and from the overall free energy change of ATP hydrolysis it was calculated that under the prevailing experimental conditions in unregulated acto-HMM 62% and in regulated acto-HMM 66% of the free energy change of ATP hydrolysis occurs after the release of phosphate from actomyosin. It is probably this part of the free energy change that is used by the muscle for the performance of work.

Bioenergetics of Na+ transport across frog skin: chemical and electrical measurements

1983 ◽  
Vol 245 (6) ◽  
pp. F691-F700 ◽  
Author(s):  
M. M. Civan ◽  
K. Peterson-Yantorno ◽  
D. R. DiBona ◽  
D. F. Wilson ◽  
M. Erecinska
Keyword(s):  
Free Energy ◽  
Frog Skin ◽  
Atp Hydrolysis ◽  
Transepithelial Transport ◽  
Base Line ◽  
Free Energies ◽  
Electrical Measurements ◽  
Far From Equilibrium ◽  
The Difference ◽  
Hydrolysis Of

Enzymatically prepared split frog skins consisted purely of epithelial cells. Electrical parameters and the cell contents of ATP, ADP, phosphocreatine (PCr), creatine, inorganic phosphate, protein, and water were measured in skins maintained at room temperature. Studies were conducted under base-line conditions, 15 and 60 min after adding vasopressin, and 30 min after adding amiloride. Intracellular ionic activities and concentrations were obtained from previous results. The data demonstrated that 1) the base-line concentration ratio of PCr/ATP was 0.53 +/- 0.03; 2) the average molar free energy of hydrolysis of intracellular ATP was approximately 15.0 kcal X mol-1 under control conditions, changing by less than or equal to 3% with changes in transport; and 3) the free energy of extruding 3 mol of Na+ and accumulating 2 mol of K+ was approximately 9.8 kcal X mol-1 under base-line conditions; the difference between the molar free energies of ATP hydrolysis and of transport work remained large, despite large changes in transepithelial transport. The simplest conclusion is that the Na+ pump of frog skin operates far from equilibrium.

Glycolytic buffering affects cardiac bioenergetic signaling and contractile reserve similar to creatine kinase

2003 ◽  
Vol 285 (2) ◽  
pp. H883-H890 ◽  
Author(s):  
Glenn J. Harrison ◽  
Michiel H. van Wijhe ◽  
Bas de Groot ◽  
Francina J. Dijk ◽  
Lori A. Gustafson ◽  
...  
Keyword(s):  
Creatine Kinase ◽  
Oxygen Consumption ◽  
Cardiac Myocyte ◽  
Atp Hydrolysis ◽  
Response Times ◽  
Diastolic Pressure ◽  
Contractile Function ◽  
Iodoacetic Acid ◽  
Rate Pressure Product ◽  
Contractile Reserve

Creatine kinase (CK) and glycolysis represent important energy-buffering processes in the cardiac myocyte. Although the role of compartmentalized CK in energy transfer has been investigated intensely, similar duties for intracellular glycolysis have not been demonstrated. By measuring the response time of mitochondrial oxygen consumption to dynamic workload jumps ( tmito) in isolated rabbit hearts, we studied the effect of inhibiting energetic systems (CK and/or glycolysis) on transcytosolic signal transduction that couples cytosolic ATP hydrolysis to activation of oxidative phosphorylation. Tyrode-perfused hearts were exposed to 15 min of the following: 1) 0.4 mM iodoacetamide (IA; n = 6) to block CK (CK activity <3% vs. control), 2) 0.3 mM iodoacetic acid (IAA; n = 5) to inhibit glycolysis (GAPDH activity <3% vs. control), or 3) vehicle (control, n = 7) at 37°C. Pretreatment tmito was similar across groups at 4.3 ± 0.3 s (means ± SE). No change in tmito was observed in control hearts; however, in IAA- and IA-treated hearts, tmito decreased by 15 ± 3% and 40 ± 5%, respectively ( P < 0.05 vs. control), indicating quicker energy supply-demand signaling in the absence of ADP/ATP buffering by CK or glycolysis. The faster response times in IAA and IA groups were independent of the size of the workload jump, and the increase in myocardial oxygen consumption during workload steps was unaffected by CK or glycolysis blockade. Contractile function was compromised by IAA and IA treatment versus control, with contractile reserve (defined as increase in rate-pressure product during a standard heart rate jump) reduced to 80 ± 8% and 80 ± 10% of baseline, respectively ( P < 0.05 vs. control), and significant elevations in end-diastolic pressure, suggesting raised ADP concentration. These results demonstrate that buffering of phosphate metabolites by glycolysis in the cytosol contributes appreciably to slower mitochondrial activation and may enhance contractile efficiency during increased cardiac workloads. Glycolysis may therefore play a role similar to CK in heart muscle.

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