ʟ-Phenylalanine Effect on Rat Diaphragm Acetylcholinesterase and Na+,K+-ATPase

1998 ◽  
Vol 53 (11-12) ◽  
pp. 1055-1060 ◽  
Author(s):  
Stylianos Tsakiris ◽  
Panagiota Kouniniotou-Krontiri ◽  
Kleopatra H. Schulpis
Keyword(s):  
Enzyme Activity ◽  
Cerebral Cortex ◽  
Atpase Activity ◽  
Ache Activity ◽  
Rat Diaphragm ◽  
Low Concentrations ◽  
Old Rats

Abstract The effect of different L-phenylalanine (Phe) concentrations (0.24-12.1 mᴍ) , on acetylcho­linesterase (AChE) and Na+,K+-ATPase activities of diaphragm homogenates from 21-day old rats and pure enzymes, was investigated at 37 °C. AChE and N a+,K+-ATPase activities were determined after preincubation with Phe. AChE activity in diaphragm homogenate or in pure eel E. electricus enzyme showed a decrease, which reached a maximum of 18% with Phe concentrations of 0.9-12.1 mᴍ. However lower Phe concentrations (0.24 mᴍ) increased the enzyme activity (by approximately 22%), only in the diaphragm homogenate. Dia­phragm-associated Na+,K+-ATPase activity showed a progressive and concentration-depen­ dent decrease, by about 30-35% in the presence of high Phe concentrations. Pure enzyme activity (from porcine cerebral cortex) was not affected by high Phe concentrations (>0.48 m M) , while it was increased by low concentrations. The above results suggest; a) A direct inactivating effect of high Phe concentrations on AChE and an indirect activating effect induced by low concentrations, b) A direct activating effect of low Phe concentrations and an indirect inactivating effect of high ones on Na+,K+-ATPase. c) The combination of high Phe concentrations effects on AChE and Na+,K+-ATPase could influence the levels of the diaphragm synaptic ACh.

ʟ-Phenylalanine Effect on Rat Brain Acetylcholinesterase and Na+,K+-ATPase

1998 ◽  
Vol 53 (3-4) ◽  
pp. 163-167 ◽  
Author(s):  
Stylianos Tsakiris ◽  
Panagiota Kouniniotou-Krontiri ◽  
Kleopatra H. Schulpis ◽  
John C. Stavridis
Keyword(s):  
Enzyme Activity ◽  
Cerebral Cortex ◽  
Atpase Activity ◽  
Direct Effect ◽  
Indirect Effect ◽  
Ache Activity ◽  
Brain Homogenate ◽  
Activity Increase ◽  
Low Concentrations ◽  
Brain Acetylcholinesterase

Abstract The effect of different L-phenylalanine (Phe) concentrations (0 .1-12.1 mᴍ) , on acetylcholinesterase (AChE ) and Na+,K+-ATPase activities of brain homogenate and pure enzymes, was investigated at 37 °C. AChE and Na+,K+-ATPase activities were determined according to Ellman G. L., Courtney D., Andres V. and Featherstone R. M. (1961), Biochem. Pharmacol. 7, 88 - 95 and Bowler K. and Tirri R. (1974), J. Neurochem. 23, 611-613 ) respectively, after preincubation with Phe. AChE activity in brain homogenate or in pure eel E.electricus enzyme showed a decrease, which reached up to 18% with concentrations of 0.9-12.1 mᴍ. Brain homogenate Na+,K+-ATPase activity showed an increase 16-65% with 0.24-0.9 mᴍ of Phe, while an activity increase of 60 -65% appeared with 0.9-12.1 mᴍ of Phe. Pure enzyme activity (from porcine cerebral cortex) was not affected by high Phe concentrations, while it was increased by low concentrations. The above results suggest: a) A direct effect of Phe on AChE, b) A direct effect of low Phe concentrations and an indirect effect of high ones on Na+,K+-ATPase.

Effect of Aging on the Activities of Acetylcholinesterase, Na+, K+-ATPase and Mg2+-ATPase in Rat Pituitary and Hypothalamus

1998 ◽  
Vol 53 (3-4) ◽  
pp. 168-172 ◽  
Author(s):  
Stylianos Tsakiris ◽  
Panagoula Angelogianni ◽  
John C. Stavridis
Keyword(s):  
Atpase Activity ◽  
Ache Activity ◽  
Energy Production ◽  
Metabolic Energy ◽  
Adult Rats ◽  
Neural Excitability ◽  
Age Related ◽  
Rat Pituitary ◽  
Old Rats

Abstract Acetylcholinesterase (AChE), Na+, K+-ATPase and Mg2+-ATPase activities were esti­mated in homogenised rat pituitary and hypothalamus of 4-and 22-month-old rats. AChE activity was not altered in the pituitary of aged com pared to adult rats, while it was found decreased by about 40% in the hypothalamus. Na+,K+-ATPase activity remained stable in the hypothalamus, while it was decreased by about 38% in the pituitary. Mg2+-ATPase activ­ity remained unchanged in the hypothalamus, but was increased by about 83% in the pitu­itary. This pituitary Na+, K+-ATPase inactivation may result in pathological mood and de­creased neural excitability and metabolic energy production in aged animals.The age-related alterations of AChE , Na+, K+-ATPase and Mg2+-ATPase activities may reflect changes in secretion and responses of some hormones of pituitary and hypothalamus.

EGTA-sensitive and -insensitive forms of particulate adenylate cyclase in rat cerebral cortex: regulation by divalent cations and GTP

1985 ◽  
Vol 63 (8) ◽  
pp. 1007-1016 ◽  
Author(s):  
P. V. Sulakhe
Keyword(s):  
Enzyme Activity ◽  
Cerebral Cortex ◽  
Adenylate Cyclase ◽  
Gray Matter ◽  
Rank Order ◽  
Divalent Cations ◽  
Rat Cerebral Cortex ◽  
Chloride Salt ◽  
Low Concentrations ◽  
Stimulation Of

Interactions of several divalent cations (Mn2+, Ca2+, Co2+, Sr2+, and Zn2+) with EGTA-inhibitable adenylate cyclase were investigated in washed membranes (particles) isolated from the gray matter of rat cerebral cortex. The EGTA-inhibitable (called sensitive) enzyme activity was assayed in the presence of Triton X-100 since this detergent caused a marked increase (up to 20-fold) in the enzyme activity. The effects of various divalent metals (all added as chloride salt) indicated the presence of two distinct sites called site I and site II. At low concentrations (less than micromolar) Mn2+, Co2+, and Ca2+ increased (up to 10-fold) the enzyme activity to the same extent and appeared to act via binding to site I (high affinity site). The rank order of affinity was Mn2+ ≥ Co2+ > Ca2+. Zn2+ showed the highest affinity and Sr2+ the lowest towards binding to site I; both these metals increased the enzyme activity to lesser extents than Mn2+, Co2+, or Ca2+. GTP was not required for the stimulation of this enzyme by low concentrations of Ca2+. The interaction of Mn2+ with site II (low affinity site) caused further increase in the enzyme activity, whereas Co2+, Ca2+, and Sr2+ were inhibitory at concentrations >10 μM. Isolated fraction contained loosely and tightly associated pools of calmodulin. Myelin basic protein, but not calcineurin, inhibited the EGTA-sensitive adenylate cyclase activity. The EGTA-insensitive enzyme activity was increased by norepinephrine by mechanisms that depended on GTP and was inhibited by Ca2+. The stimulation of the EGTA-insensitive enzyme modulated the Mg2+ requirement such that Mg2+ binding to the low affinity site (site II) apparently occurred with higher affinity. The likely significance of these results is discussed with regard to (i) the presence of two classes of adenylate cyclase in rat cerebral cortex gray matter and (ii) the regulation of their activities by calmodulin-requiring and GTP-requiring mechanisms.

scholarly journals In vivo and in vitro effects of fructose on rat brain acetylcholinesterase activity: an ontogenetic study

2014 ◽  
Vol 86 (4) ◽  
pp. 1919-1926 ◽  
Author(s):  
CARINE A. GUIMARÃES ◽  
MAIRIS S. BIELLA ◽  
ABIGAIL LOPES ◽  
PEDRO F. DEROZA ◽  
MARIANA B. OLIVEIRA ◽  
...  
Keyword(s):  
Cerebral Cortex ◽  
Ache Activity ◽  
Young Patients ◽  
Brain Structures ◽  
Acetylcholinesterase Activity ◽  
Control Group ◽  
Inherited Disorders ◽  
Old Rats

Increased fructose concentrations are the biochemical hallmark of fructosemia, a group of inherited disorders on the metabolic pathway of this sugar. The main clinical findings observed in patients affected by fructosemia include neurological abnormalities with developmental delay, whose pathophysiology is still undefined. In the present work we investigated the in vitro and in vivo effects of fructose on acetylcholinesterase (AchE) activity in brain structures of developing rats. For the in vitro experiments, fructose was added at increasing concentrations to the incubation medium. It was observed that fructose provoked an inhibition of acetylcholinesterase activity in cerebral cortex of 30-day-old-rats, even at low concentrations (0.1 mM). For the in vivo experiments, rats were killed 1 h after a single fructose administration (5 µmol/g). Control group received the same volume of saline solution. We found that AchE activity was increased in cerebral cortex of 30- and 60-day-old rats receiving fructose administration. Finally, we observed that AchE activity was unaffected by acute fructose administration in cerebral cortex, striatum or hippocampus of 15- and 90-day-old rats. The present data suggest that a disruption in cholinergic homeostasis may be involved in the pathophysiology of brain damage observed in young patients affected by fructosemia.

´Chloride-stimulated ATPase ’ activity in Limonium vulgare Mill

1982 ◽  
Vol 299 (1097) ◽  
pp. 459-468 ◽  
Keyword(s):  
Enzyme Activity ◽  
Atpase Activity ◽  
Chloride Ions ◽  
Cautionary Tale ◽  
Monovalent Anion ◽  
Low Concentrations ◽  
Limonium Vulgare ◽  
Chloride Pump ◽  
Sea Lavender ◽  
Salt Secretion

Limonium vulgare Mill, (sea lavender) is a saltmarsh plant in whose leaves are embedded multicellular glands for the excretion of salt. Physiological studies have shown that the basis of the salt secretion mechanism appears to be salt-inducible, ATP-powered pumping of chloride ions out of gland cells. We have been investigating a ‘chloridestimulated’ ATPase activity of solubilized Limonium leafmicrosomes, which we thought was almost certainly part of a chloride pump involved in salt secretion because the properties of the enzyme activity correlated so well with the characteristics of salt secretion. Methods of purifying this activity on hexyl agarose and by selective solubilization with low concentrations of neutral detergent are presented. These and other results have made it necessary to revise our understanding of earlier findings on the purification of the ‘ Cl-stimulated ’ ATPase on Sepharose- N -caproyl galactosamine. Recent results indicate that the apparent ‘ stimulation ’ by chloride can be accounted for by an inhibition of salt-inducible ATPase activity by the ‘control’, non-Cl-, monovalent anion, benzene sulphonate, adopted because it resembles chloride yet did not support salt-secretion. Our results demonstrate some of the dangers in interpreting measurements of ion-stimulated ATPase activity, and make an instructive ‘ cautionary tale’.

Ontogeny of Na-K-ATPase activity in thick ascending limb and of concentrating capacity

1985 ◽  
Vol 249 (5) ◽  
pp. F723-F728 ◽  
Author(s):  
S. Rane ◽  
A. Aperia
Keyword(s):  
Enzyme Activity ◽  
Atpase Activity ◽  
Corticosterone Level ◽  
Thick Ascending Limb ◽  
Pronounced Increase ◽  
Serum Corticosterone ◽  
Single Nephron ◽  
Concentrate Urine ◽  
Old Rats ◽  
Made In

Na-K-ATPase activity in the thick ascending limb of Henle (TAL) and the capacity to concentrate urine was determined in 12-, 16-, 20-, 30-, and 40-day-old rats. The most pronounced increase in enzyme activity occurred between 16 and 20 days of age. The relation between enzyme activity in the cortical and medullary TAL was found to be the same in 16-, 20-, and 40-day-old rats, and most enzyme determinations were made in the medullary TAL. The development of Na-K-ATPase activity in TAL and urinary concentrating capacity followed the same pattern. The developmental increase in Na-K-ATPase activity and concentrating capacity between 16 and 20 days of age was accompanied by an increase in serum corticosterone level and was abolished by adrenalectomy. Treatment with glucocorticoid hormones precociously induced Na-K-ATPase activity and concentrating capacity in 13- to 16-day-old rats but had no effect on Na-K-ATPase activity in 17- to 20-day-old rats. The increase in enzyme activity from 20 to 40 days of age was accompanied by an increase in the single nephron glomerular filtration rate. The results suggest that Na-K-ATPase activity in the TAL is an important determinant of the concentrating capacity during development. The developmental surge in Na-K-ATPase activity and concentrating capacity between 16 and 20 days of age is probably set off by the rise in the serum corticosterone level.

Serum Cholinesterase Variants: Examination of Several Differential Inhibitors, Salts, and Buffers Used to Measure Enzyme Activity

1971 ◽  
Vol 17 (3) ◽  
pp. 183-191 ◽  
Author(s):  
Philip J Garry
Keyword(s):  
Enzyme Activity ◽  
Sodium Fluoride ◽  
Phosphate Buffer ◽  
Divalent Cations ◽  
Kinetic Studies ◽  
Competitive Inhibitor ◽  
Serum Cholinesterase ◽  
Low Concentrations

Abstract Dibucaine, used as a differential inhibitor with acetyl-, propionyl-, and butyrylthiocholine as substrate, clearly identified the "usual" and "atypical" serum cholinesterases. Succinylcholine was also used successfully as a differential inhibitor with butyrylthiocholine as substrate. Sodium fluoride, used as a differential inhibitor, gave conflicting results, depending on whether Tris or phosphate buffer was used in the assay. Mono- and divalent cations (NaCl, KCl, MgCl2, CaCl2, and BaCl2) activated the "usual" and inhibited the "atypical" enzyme at low concentrations. The "usual" enzyme had the same activity in 0.05 mol of Tris or phosphate buffer per liter, while the heterozygous and "atypical" enzymes showed 12 and 42% inhibition, respectively, when assayed in the phosphate buffer. Kinetic studies showed the phosphate acted as a competitive inhibitor of "atypical" enzyme. Km values, determined for "usual" and "atypical" enzymes, were 0.057 and 0.226 mmol/liter, respectively, with butyrylthiocholine as substrate.

scholarly journals Novel Substrates for Kinases Involved in the Biosynthesis of Inositol Pyrophosphates and Their Enhancement of ATPase Activity of a Kinase

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3601
Author(s):  
Raja Mohanrao ◽  
Ruth Manorama ◽  
Shubhra Ganguli ◽  
Mithun C. Madhusudhanan ◽  
Rashna Bhandari ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Atpase Activity ◽  
Catalytic Domain ◽  
Inositol Phosphate ◽  
Substrate Recognition ◽  
Competitive Inhibitor ◽  
Inositol Polyphosphates ◽  
Inositol Pyrophosphate ◽  
Phosphate Donor ◽  
Inositol Pyrophosphates

IP6K and PPIP5K are two kinases involved in the synthesis of inositol pyrophosphates. Synthetic analogs or mimics are necessary to understand the substrate specificity of these enzymes and to find molecules that can alter inositol pyrophosphate synthesis. In this context, we synthesized four scyllo-inositol polyphosphates—scyllo-IP5, scyllo-IP6, scyllo-IP7 and Bz-scyllo-IP5—from myo-inositol and studied their activity as substrates for mouse IP6K1 and the catalytic domain of VIP1, the budding yeast variant of PPIP5K. We incubated these scyllo-inositol polyphosphates with these kinases and ATP as the phosphate donor. We tracked enzyme activity by measuring the amount of radiolabeled scyllo-inositol pyrophosphate product formed and the amount of ATP consumed. All scyllo-inositol polyphosphates are substrates for both the kinases but they are weaker than the corresponding myo-inositol phosphate. Our study reveals the importance of axial-hydroxyl/phosphate for IP6K1 substrate recognition. We found that all these derivatives enhance the ATPase activity of VIP1. We found very weak ligand-induced ATPase activity for IP6K1. Benzoyl-scyllo-IP5 was the most potent ligand to induce IP6K1 ATPase activity despite being a weak substrate. This compound could have potential as a competitive inhibitor.

Metabolic importance of Na+/K+-ATPase activity during sea urchin development.

1997 ◽  
Vol 200 (22) ◽  
pp. 2881-2892 ◽  
Author(s):  
P Leong ◽  
D Manahan
Keyword(s):  
Enzyme Activity ◽  
Atpase Activity ◽  
Sea Urchin ◽  
Sodium Pump ◽  
Sea Water ◽  
Strongylocentrotus Purpuratus ◽  
Lytechinus Pictus ◽  
Stimulation Of

Early stages of animal development have high mass-specific rates of metabolism. The biochemical processes that establish metabolic rate and how these processes change during development are not understood. In this study, changes in Na+/K+-ATPase activity (the sodium pump) and rate of oxygen consumption were measured during embryonic and early larval development for two species of sea urchin, Strongylocentrotus purpuratus and Lytechinus pictus. Total (in vitro) Na+/K+-ATPase activity increased during development and could potentially account for up to 77 % of larval oxygen consumption in Strongylocentrotus purpuratus (pluteus stage) and 80 % in Lytechinus pictus (prism stage). The critical issue was addressed of what percentage of total enzyme activity is physiologically active in living embryos and larvae and thus what percentage of metabolism is established by the activity of the sodium pump during development. Early developmental stages of sea urchins are ideal for understanding the in vivo metabolic importance of Na+/K+-ATPase because of their small size and high permeability to radioactive tracers (86Rb+) added to sea water. A comparison of total and in vivo Na+/K+-ATPase activities revealed that approximately half of the total activity was utilized in vivo. The remainder represented a functionally active reserve that was subject to regulation, as verified by stimulation of in vivo Na+/K+-ATPase activity in the presence of the ionophore monensin. In the presence of monensin, in vivo Na+/K+-ATPase activities in embryos of S. purpuratus increased to 94 % of the maximum enzyme activity measured in vitro. Stimulation of in vivo Na+/K+-ATPase activity was also observed in the presence of dissolved alanine, presumably due to the requirement to remove the additional intracellular Na+ that was cotransported with alanine from sea water. The metabolic cost of maintaining the ionic balance was found to be high, with this process alone accounting for 40 % of the metabolic rate of sea urchin larvae (based on the measured fraction of total Na+/K+-ATPase that is physiologically active in larvae of S. purpuratus). Ontogenetic changes in pump activity and environmentally induced regulation of reserve Na+/K+-ATPase activity are important factors that determine a major proportion of the metabolic costs of sea urchin development.

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