scholarly journals Glyceride lipases in nerve endings of guinea-pig brain and their stimulation by noradrenaline, 5-hydroxytryptamine and adrenaline

1973 ◽  
Vol 132 (2) ◽  
pp. 233-248 ◽  
Author(s):  
O. S. Vyvoda ◽  
C. E. Rowe
Keyword(s):  
Guinea Pig ◽  
Synaptic Vesicles ◽  
Protein Concentration ◽  
Synaptic Membranes ◽  
Ph Optimum ◽  
Triglyceride Lipase ◽  
Monoglyceride Lipase ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of ◽  
Guinea Pig Brain

1. Combined guinea-pig cortex and cerebellum was shown to contain triglyceride lipase, diglyceride lipase and monoglyceride lipase, which were assayed by the release of [1-14C]palmitate from [1-14C]palmitoylglycerol esters. Triglyceride lipase and diglyceride lipase were found in all particulate fractions. 2. With osmotically ruptured synaptosomes the rates of release of palmitate from glyceryl tripalmitate and glyceryl dipalmitate were 7–25μmol/h per g of protein and 0.18–0.69mmol/h per g of protein respectively. The logarithm of the rate of hydrolysis of glyceryl monopalmitate increased linearly with the logarithm of protein concentration. The pH optima of triglyceride lipase and diglyceride lipase were between 7 and 8. The pH optimum for monoglyceride lipase was approx. 8. 3. Triglyceride lipase and diglyceride lipase of osmotically ruptured synaptosomes were stimulated by noradrenaline, 5-hydroxytryptamine and adrenaline. Triglyceride lipase of isolated synaptic membranes was stimulated by 0.01–1mm-noradrenaline. Aging of membranes at 0°C decreased activity, which could still be stimulated by noradrenaline. Diglyceride lipase of isolated membranes was stimulated by 1μm–1mm-noradrenaline. The activity of triglyceride lipase in isolated synaptic vesicles was diminished by 1mm-5-hydroxytryptamine.

scholarly journals The stimulation by transmitter substances and putative transmitter substances of the net activity of phospholipase A2 of synaptic membranes of cortex of guinea-pig brain

1975 ◽  
Vol 148 (2) ◽  
pp. 197-208 ◽  
Author(s):  
R J Gullis ◽  
C E Rowe
Keyword(s):  
Guinea Pig ◽  
Phospholipase A2 ◽  
Synaptic Vesicles ◽  
Optimum Concentration ◽  
Synaptic Membranes ◽  
Phospholipase A1 ◽  
Response Curves ◽  
Pig Brain ◽  
Hydrolysis Of ◽  
Guinea Pig Brain

1. The distribution of the hydrolyses of phosphatidylcholine by phospholipase A2 and phospholipase A1, and the hydrolysis of lysophosphatidylcholine by lysophospholipase, in subcellular and subsynaptosomal fractions of cerebral cortices of guinea-pig brain, was determined. 2. Noradrenaline stimulated hydrolysis by phospholipase A2 in whole synaptosomes, synaptic membranes and fractions containing synaptic vesicles. 3. Stimulation of hydrolysis by phospholipase A2 in synaptic membranes by noradrenaline was enhanced by CaCl2, and by a mixture of ATP and MgCl2. The optimum concentration of CaCl2, in the presence of ATP and MgCl2, for stimulation by 10 muM-noradrenaline was in the range 1-10muM. The optimum concentration for ATP-2MgCl2 in the presence of 1 muM-CaCl2 was in the range 0.1-1mM. 4. Hydrolysis by phospholipase A2 of synaptic membranes was also stimulated by acetylcholine, carbamoylcholine, 5-hydroxytryptamine, dopamine (3,4-dihydroxyphenethylamine), histamine, psi-aminobutyric acid, glutamic acid and aspartic acid. With appropriate concentrations of cofactors, sigmoidal dose-response curves were obtained, half-maximum stimulations being obtained with concentrations of stimulant in the range 0.1-1muM. 5. Taurine also stimulated hydrolysis of phosphatidylcholine by phospholipase A2. There were only slight stimulations with methylamine, ethylenediamine or spermidine. No stimulation was obtained with glucagon.

scholarly journals Stimulation of the production of unesterified fatty acids in nerve endings of guinea-pig brain in vitro by noradrenaline and 5-hydroxytryptamine

1972 ◽  
Vol 126 (3) ◽  
pp. 575-585 ◽  
Author(s):  
C. J. Price ◽  
C. E. Rowe
Keyword(s):  
Fatty Acids ◽  
Cerebral Cortex ◽  
Guinea Pig ◽  
Synaptic Vesicles ◽  
Nerve Endings ◽  
Synaptic Membranes ◽  
Pig Brain ◽  
Guinea Pig Brain ◽  
Stimulation Of

1. Noradrenaline (1mm) and 5-hydroxytryptamine (1mm) stimulated the production of unesterified palmitate, oleate, stearate and arachidonate in nerve endings (synaptosomes) isolated from combined guinea-pig cerebral cortex and cerebellum. 2. Iproniazid phosphate (0.36mm) increased the concentrations of the same acids in osmotically ruptured synaptosomes. Further addition of 1mm-noradrenaline or 1mm-5-hydroxytryptamine reversed this increase. 3. Noradrenaline (0.01mm) stimulated the production of unesterified fatty acids in isolated synaptic membranes. 5-Hydroxytryptamine (0.01mm) stimulated the production of unesterified fatty acids in synaptic membranes and synaptic vesicles.

Polarographic study of hydrolysis of [8-lysine]vasopressin and its derivatives with blood serum of pregnant women

1980 ◽  
Vol 45 (4) ◽  
pp. 1099-1108 ◽  
Author(s):  
Mikuláš Chavko ◽  
Michal Bartík ◽  
Evžen Kasafírek
Keyword(s):  
Blood Serum ◽  
Pregnant Women ◽  
Degree Of Hydrolysis ◽  
Polarographic Study ◽  
Ph Optimum ◽  
Lysine Vasopressin ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of ◽  
Vasopressin Analogues

A polarographic study of the hydrolysis of [8-lysine]vasopressin and some hormonogens of the vasopressin series with the blood serum of women in the last week of pregnancy was studied. The dependence of hydrolysis on pH (pH optimum: 7.4-7.50, substrate concentration (Km 1.2 . 10-5M), pH stability and thermal stability were determined. The rate of hydrolysis of individual vasopressin analogues decreases in the order: [8-lysine]vasopressin > Nα-glycyl-prolyl[8-lysine]-vasopressin > Nα-leucyl-[8-lysine]vasopressin > Nα-alanyl-[8-lysine]vasopressin > Nα-phenyl alanyl-[8-lysine]vasopressin > Nα-diglycyl-[8-lysine]vasopressin > Nα-prolyl-[8-lysine]vasopressin > Nα-triglycyl-[8-lysine]vasopressin > Nα-sarcosyl-glycyl-[8-lysine]vasopressin. The degree of hydrolysis gradually increases to a multiple with the length of the pregnancy in consequence of the presence of oxytocine. However, vasopressin is also hydrolysed to a small extent with the enzymes from the blood sera of non-pregnant women. Under similar analytical conditions oxytocin was not hydrolysed with the sera of non-pregnant women and therefore oxytocin is a more suitable substrate than vasopressin for polarographic determination of serum oxytocinase.

scholarly journals Evidence for the regulation of guinea-pig heart microsomal phosphatidylcholine-hydrolysing phospholipase A1 by guanosine 5′-[γ-thio]triphosphate

1992 ◽  
Vol 288 (3) ◽  
pp. 965-968 ◽  
Author(s):  
K Badiani ◽  
X Lu ◽  
G Arthur
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Guinea Pig ◽  
Molecular Species ◽  
Inhibitory Effect ◽  
Phospholipase A1 ◽  
Guinea Pig Heart ◽  
Substrate Specificities ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

We have recently characterized lysophospholipase A2 activities in guinea-pig heart microsomes and postulated that these enzymes act sequentially with phospholipases A1 to release fatty acids selectively from phosphatidylcholine (PC) and phosphatidylethanolamine, thus providing an alternative route to the phospholipase A2 mode of release. In a further investigation of the postulated pathway, we have characterized the PC-hydrolysing phospholipase A1 in guinea-pig heart microsomes. Our results show that the enzyme may have a preference for substrates with C16:0 over C18:0 at the sn-1 position. In addition, although the enzyme cleaves the sn-1 fatty acid, the rate of hydrolysis of PC substrates with C16:0 at the sn-1 position was influenced by the nature of the fatty acid at the sn-2 position. The order of decreasing preference was C18:2 > C20:4 = C18:1 > C16:0. The hydrolyses of the molecular species were differentially affected by heating at 60 degrees C. An investigation into the effect of nucleotides on the activity of the enzyme showed that guanosine 5′-[gamma-thio]triphosphate (GTP[S]) inhibited the hydrolysis of PC by phospholipase A1 activity, whereas GTP, guanosine 5′-[beta-thio]diphosphate (GDP[S]), GDP, ATP and adenosine 5′-[gamma-thio]triphosphate (ATP[S]) did not affect the activity. The inhibitory effect of GTP[S] on phospholipase A1 activity was blocked by preincubation with GDP[S]. A differential effect of GTP[S] on the hydrolysis of different molecular species was also observed. Taken together, the results of this study suggest the presence of more than one phospholipase A1 in the microsomes with different substrate specificities, which act sequentially with lysophospholipase A2 to release linoleic or arachidonic acid selectively from PC under resting conditions. Upon stimulation and activation of the G-protein, the release of fatty acids would be inhibited.

HYDROLYSIS OF GLYCEROLPHOSPHATIDES BY PLASTID PHOSPHATIDASE C

1956 ◽  
Vol 34 (5) ◽  
pp. 967-980 ◽  
Author(s):  
Morris Kates
Keyword(s):  
Ethyl Ether ◽  
Phosphatidyl Choline ◽  
Phosphatidyl Ethanolamine ◽  
Enzymatic Reaction ◽  
Phosphatidyl Serine ◽  
Ph Optimum ◽  
Soybean Phosphatide ◽  
Optimum Ph ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

Studies of the influence of structural variation in the glycerolphosphatide molecule on the hydrolysis of this class of compounds by plastid phosphatidase C showed that the presence of both fatty acid ester groups is necessary for enzymatic reaction; that release of nitrogenous bases occurred, in the presence of ethyl ether, from phosphatidyl cholines, phosphatidyl ethanolamine, and phosphatidyl serine; and that a phosphatidyl choline was hydrolyzed more rapidly than the corresponding phosphatidyl ethanolamine or phosphatidyl serine. The rate of hydrolysis of phosphatidyl choline was influenced greatly by the chain length and degree of unsaturation of the fatty acids. The corresponding phosphatidic acid formed in the hydrolysis of (dipalmitoyl)- or (dipalmitoleyl)-lecithin by carrot phosphatidase C was isolated. Studies on the hydrolysis of crude soybean phosphatide by phosphatidase C showed that both choline and ethanolamine were liberated in the absence of ethyl ether, at an optimum pH of 4.8; in the presence of ether, the rate of liberation of each base was increased, and the pH optimum was between 4.8 and 6. Soybean phosphatide probably contains a substance that stimulates the enzymatic hydrolysis.

HYDROLYSIS OF GLYCEROLPHOSPHATIDES BY PLASTID PHOSPHATIDASE C

1956 ◽  
Vol 34 (1) ◽  
pp. 967-980 ◽  
Author(s):  
Morris Kates
Keyword(s):  
Ethyl Ether ◽  
Phosphatidyl Choline ◽  
Phosphatidyl Ethanolamine ◽  
Enzymatic Reaction ◽  
Phosphatidyl Serine ◽  
Ph Optimum ◽  
Soybean Phosphatide ◽  
Optimum Ph ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

Studies of the influence of structural variation in the glycerolphosphatide molecule on the hydrolysis of this class of compounds by plastid phosphatidase C showed that the presence of both fatty acid ester groups is necessary for enzymatic reaction; that release of nitrogenous bases occurred, in the presence of ethyl ether, from phosphatidyl cholines, phosphatidyl ethanolamine, and phosphatidyl serine; and that a phosphatidyl choline was hydrolyzed more rapidly than the corresponding phosphatidyl ethanolamine or phosphatidyl serine. The rate of hydrolysis of phosphatidyl choline was influenced greatly by the chain length and degree of unsaturation of the fatty acids. The corresponding phosphatidic acid formed in the hydrolysis of (dipalmitoyl)- or (dipalmitoleyl)-lecithin by carrot phosphatidase C was isolated. Studies on the hydrolysis of crude soybean phosphatide by phosphatidase C showed that both choline and ethanolamine were liberated in the absence of ethyl ether, at an optimum pH of 4.8; in the presence of ether, the rate of liberation of each base was increased, and the pH optimum was between 4.8 and 6. Soybean phosphatide probably contains a substance that stimulates the enzymatic hydrolysis.

scholarly journals The catabolism of plasmenylcholine in the guinea pig heart

1986 ◽  
Vol 236 (2) ◽  
pp. 475-480 ◽  
Author(s):  
G Arthur ◽  
L Page ◽  
T Mock ◽  
P C Choy
Keyword(s):  
Guinea Pig ◽  
Phospholipase A2 ◽  
High Specificity ◽  
Experimental Conditions ◽  
Ph Optimum ◽  
Major Pathway ◽  
Guinea Pig Heart ◽  
Mitochondrial Fractions ◽  
Wide Range ◽  
Hydrolysis Of

The hydrolysis of the alkenyl bonds of plasmenylcholine and plasmenylethanolamine by plasmalogenase, followed by hydrolysis of the resultant lysophospholipid by lysophospholipase, has been postulated as the major pathway for the catabolism of these plasmalogens. However, the postulation was based solely on the presence of plasmalogenase activity towards plasmenylethanolamine and plasmenylcholine in the brain. In this study we have demonstrated the absence of plasmalogenase activity for plasmenylcholine in the guinea pig heart under a wide range of experimental conditions. Plasmenylcholine was hydrolysed by phospolipase A2 activities in cardiac microsomal, mitochondrial and cytosolic fractions. Phospholipase A2 activities in these fractions had an alkaline pH optimum and were enhanced by Ca2+. The enzymes also displayed high specificity for plasmenylcholine with linoleoyl or oleoyl at the C-2 position. Lysoplasmalogenase activity for lysoplasmenycholine was also detected and characterized in the microsomal and mitochondrial fractions. Since the cardiac plasmalogenase is only active towards plasmenylethanolamine but not plasmenylcholine, the catabolism of these two plasmalogens must be different from each other. We postulate that the major pathway for the catabolism of plasmenycholine involves the hydrolysis of the C-2 fatty acid by phospholipase A2, and hydrolysis of the vinyl ether group of the resultant lysoplasmenylcholine by lysoplasmalogenase.

scholarly journals Calcium-activated hydrolysis of phosphatidyl-myo-inositol 4-phosphate and phosphatidyl-myo-inositol 4,5-bisphosphate in guinea-pig synaptosomes

1978 ◽  
Vol 176 (2) ◽  
pp. 541-552 ◽  
Author(s):  
Harry D. Griffin ◽  
John N. Hawthorne
Keyword(s):  
Guinea Pig ◽  
Inositol Phosphate ◽  
Significant Loss ◽  
Ionophore A23187 ◽  
Synaptosomal Plasma Membrane ◽  
Hydrolysis Of ◽  
Guinea Pig Brain ◽  
Significant Production

1. Addition of the bivalent ionophore A23187 to synaptosomes isolated from guinea-pig brain cortex and labelled with [32P]phosphate in vitro or in vivo caused a marked loss of radioactivity from phosphatidyl-myo-inositol 4-phosphate (diphosphoinositide) and phosphatidyl-myo-inositol 4,5-bisphosphate (triphosphoinositide) and stimulated labelling of phosphatidate. No change occurred in the labelling of other phospholipids. 2. In conditions that minimized changes in internal Mg2+ concentrations, the effect of ionophore A23187 on labelling of synaptosomal di- and tri-phosphoinositide was dependent on Ca2+ and was apparent at Ca2+ concentrations in the medium as low as 10−5m. 3. An increase in internal Mg2+ concentration stimulated incorporation of [32P]phosphate into di- and tri-phosphoinositide, whereas lowering internal Mg2+ decreased labelling. 4. Increased labelling of phosphatidate was independent of medium Mg2+ concentration and apparently only partly dependent on medium Ca2+ concentration. 5. The loss of label from di- and tri-phosphoinositide caused by ionophore A23187 was accompanied by losses in the amounts of both lipids. 6. Addition of excess of EGTA to synaptosomes treated with ionophore A23187 in the presence of Ca2+ caused a rapid resynthesis of di- and tri-phosphoinositide and a further stimulation of phosphatidate labelling. 7. Addition of ionophore A23187 to synaptosomes labelled in vivo with [3H]inositol caused a significant loss of label from di- and tri-phosphoinositide, but not from phosphatidylinositol. There was a considerable rise in labelling of inositol diphosphate, a small increase in that of inositol phosphate, but no significant production of inositol triphosphate. 8. 32P-labelled di- and tri-phosphoinositides appeared to be located in the synaptosomal plasma membrane. 9. The results indicate that increased Ca2+ influx into synaptosomes markedly activates triphosphoinositide phosphatase and diphosphoinositide phosphodiesterase, but has little or no effect on phosphatidylinositol phosphodiesterase.

scholarly journals FREE-FLOW ELECTROPHORETIC SEPARATION AND ELECTRICAL SURFACE PROPERTIES OF SUBCELLULAR PARTICLES FROM GUINEA PIG BRAIN

1971 ◽  
Vol 49 (2) ◽  
pp. 235-246 ◽  
Author(s):  
K. J. Ryan ◽  
H. Kalant ◽  
E. Llewellyn Thomas
Keyword(s):  
Guinea Pig ◽  
Synaptic Vesicles ◽  
Succinic Dehydrogenase ◽  
Free Flow ◽  
Electrophoretic Separation ◽  
Charge Densities ◽  
Zeta Potentials ◽  
Pig Brain ◽  
Choline Acetylase ◽  
Guinea Pig Brain

Continuous free-flow electrophoretic separation has been used to obtain relatively pure preparations of synaptosomes and synaptic vesicles from crude fractions of guinea pig brain homogenates. Measurements of the contents of protein, neuraminic acid, and bound acetylcholine; the activities of succinic dehydrogenase, adenosine triphosphatase, choline acetylase, and 5'-nucleotidase; and the uptake of 14C-labeled choline arid acetylcholine in the presence and absence of hemicholinium, all confirm the electron microscope evidence that the electrophoretic preparations are at least as pure as those obtained by ultracentrifugal methods. The electrophoretic mobility measurements have been used to calculate zeta potentials and surface charge densities for these particles.

scholarly journals 2-acyl-sn-glycero-3-phosphoethanolamine lysophospholipase A2 activity in guinea-pig heart microsomes

1991 ◽  
Vol 275 (2) ◽  
pp. 393-398 ◽  
Author(s):  
K Badiani ◽  
G Arthur
Keyword(s):  
Guinea Pig ◽  
High Specificity ◽  
Selective Hydrolysis ◽  
Guinea Pig Heart ◽  
Similar Activity ◽  
Optimum Ph ◽  
Different Characteristics ◽  
Hydrolysis Of ◽  
Guinea Pig Brain ◽  
Lysophospholipase Activity

We have recently described a lysophospholipase A2 activity in guinea-pig heart microsomes that hydrolyses 2-acyl-sn-glycero-3-phosphocholine (2-acyl-GPC). The presence of a similar activity that hydrolyses 2-acyl-sn-glycero-3-phosphoethanolamine (2-acyl-GPE) was not known. In this study, a lysophospholipase A2 activity in guinea-pig heart microsomes that hydrolyses 2-acyl-GPE has been characterized. The enzyme did not require Ca2+ for activity and exhibited a high specificity for 2-arachidonoyl-GPE and 2-linoleoyl-GPE over 2-oleoyl-GPE and 2-palmitoyl-GPE. The specificity for these unsaturated substrates was observed in the presence and absence of detergents. Selective hydrolysis of 2-arachidonoyl-GPE over 2-palmitoyl-GPE was observed when equimolar quantities of the two substrates were incubated with the enzyme. There was no preferential hydrolysis of either 2-linoleoyl- or 2-arachidonoyl-GPE when presented individually or as a mixture. Significant differences in the characteristics of 2-acyl-GPE-hydrolysing and 2-acyl-GPC-hydrolysing activities included differences in their optimum pH, the effect of Ca2+ and their acyl specificities. Taken together, these results suggest that the two activities are catalysed by different enzymes. 2-Acyl-GPE lysophospholipase activity with a preference for 2-arachidonoyl-GPE over 2-oleoyl-GPE was observed in guinea-pig brain, liver, kidney and lung microsomes. Lysophospholipase A1 activity that catalyses the hydrolysis of 1-acyl-GPE was also present in guinea-pig heart microsomes and had different characteristics from the 2-acyl-GPE-hydrolysing activity, including a preference for saturated over unsaturated substrates. The 2-acyl-GPE lysophospholipase A2 activity appeared to be distinct from Ca(2+)-independent phospholipase A2. The characteristics of the 2-acyl-GPE lysophospholipase A2 suggest it could play a role in the selective release of arachidonic and linoleic acids for further metabolism in cells.

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