The Existence of a Long-Chain Acyl-CoA Synthetase in Homogenates of Human Blood Platelets

1971 ◽  
Vol 28 (3) ◽  
pp. 261-265 ◽  
Author(s):  
M. Farstad ◽  
J. Sander
Keyword(s):  
Human Blood ◽  
Blood Platelets ◽  
Chain Acyl ◽  
Human Blood Platelets ◽  
Long Chain

scholarly journals Identical subcellular distribution of palmitoyl-CoA and arachidonoyl-CoA synthetase activities in human blood platelets

1989 ◽  
Vol 261 (1) ◽  
pp. 71-76 ◽  
Author(s):  
A M Bakken ◽  
M Farstad
Keyword(s):  
Enzyme Activity ◽  
Arachidonic Acid ◽  
Human Blood ◽  
Blood Platelets ◽  
The Other ◽  
Heat Inactivation ◽  
Tubular System ◽  
Chain Acyl ◽  
Human Blood Platelets ◽  
Long Chain

Fractionation of human blood platelets showed that palmitoyl-CoA synthetase and arachidonoyl-CoA synthetase activities had an identical distribution among subcellular fractions. The activity was highest with arachidonic acid as substrate in all fractions, with an enzyme activity of 50 nmol/min per mg of protein, in a ‘dense-tubular-system’-enriched fraction. The ratio activities with arachidonate and palmitate as substrates was about 1.5 in all fractions. Heat inactivation did not distinguish between arachidonoyl-CoA synthetase and a palmitoyl-CoA synthetase. On the other hand, heat inactivation indicated two pools of long-chain acyl-CoA synthetases: one in a mitochondria- and one in the dense-tubular-system-enriched fraction.

The content of coenzyme A, acetyl-CoA and long-chain acyl-CoA in human blood platelets

1982 ◽  
Vol 126 (3) ◽  
pp. 307-313 ◽  
Author(s):  
Ole C. Ingebretsen ◽  
Anne M. Bakken ◽  
Mikael Farstad
Keyword(s):  
Human Blood ◽  
Coenzyme A ◽  
Blood Platelets ◽  
Acetyl Coa ◽  
Chain Acyl ◽  
Human Blood Platelets ◽  
Long Chain

scholarly journals Identity between palmitoyl-CoA synthetase and arachidonoyl-CoA synthetase in human platelet?

1991 ◽  
Vol 274 (1) ◽  
pp. 145-152 ◽  
Author(s):  
A M Bakken ◽  
M Farstad ◽  
H Holmsen
Keyword(s):  
Fatty Acids ◽  
Blood Platelets ◽  
Saturated Fatty Acids ◽  
Synthetase Activity ◽  
Long Chain Fatty Acids ◽  
Platelet Protein ◽  
Chain Acyl ◽  
Triton X ◽  
Human Blood Platelets ◽  
Long Chain

Apparent Km values have been determined for the substrates ATP, CoA and fatty acids for the long-chain acyl-CoA synthetase (EC 6.2.1.3) reaction in lysates of human blood platelets. The apparent Km for ATP was higher for saturated fatty acids (C12:0 to C18:0) than for unsaturated acids (C18:1 to C22:6). Other apparent Km values were very similar for all long-chain fatty acids tested. Palmitic acid inhibited the formation of [14C]arachidonoyl-CoA, and arachidonic acid inhibited the formation of [14C]palmitoyl-CoA, with [14C]arachidonate or [14C]palmitate respectively as substrate. After chromatography of Triton X-100-extracted platelet protein in several systems (hydroxyapatite, DEAE-Sepharose, Sephacryl S-200 HR, CoA-Sepharose, Sephadex G-100 and AcA 34), both arachidonoyl-CoA synthetase and palmitoyl-CoA synthetase activities were eluted together in the various protein peaks, and with approximately the same ratio of activities in all peaks. After some purification steps (DEAE-Sepharose and Sephacryl S-200 HR), the acyl-CoA synthetase activity was up to 37 nmol/min per mg of protein with [14C]palmitate as substrate, and up to 116 nmol/min per mg of protein with [14C]arachidonate as substrate. The purification was respectively about 8- and 10-fold. The results indicate that palmitoyl-CoA (or unspecific) synthetase and arachidonoyl-CoA (or specific) synthetase are in fact the same enzyme, in agreement with previously reported results from this laboratory.

On the Mechanism by which Cell Contact Induces the Release Reaction of Blood Platelets; the Effect of Cationic Polymers

1972 ◽  
Vol 27 (01) ◽  
pp. 121-133 ◽  
Author(s):  
P Massini ◽  
E. F Lüscher
Keyword(s):  
Human Blood ◽  
Calcium Ions ◽  
Blood Platelets ◽  
Cell Contact ◽  
Second Phase ◽  
Cationic Polymers ◽  
Release Reaction ◽  
Per Se ◽  
Human Blood Platelets

SummaryHuman blood platelets are aggregated by the basic polymers polylysine and DEAE- dextran. Under certain conditions a second phase of aggregation, concomitant with the release reaction, is elicited. The presence of ADP, calcium ions and a plasmatic cofactor within the primary aggregates are necessary for the induction of the release reaction. These experiments demonstrate that cell contact per se does not lead to a release reaction ; in order to become effective it must take place in the presence of ADP.

Chromatographic Isolation of the LDH-Isoenzymes of Human Blood Platelets and an Investigation of Their Enzyme Kinetics

1968 ◽  
Vol 20 (03/04) ◽  
pp. 301-313 ◽  
Author(s):  
W Schneider ◽  
K Schumacher ◽  
B Thiede ◽  
R Gross
Keyword(s):  
Human Blood ◽  
Blood Platelets ◽  
Deae Cellulose ◽  
Order Reaction ◽  
Kinetic Properties ◽  
Ldh Isoenzymes ◽  
Kinetic Investigations ◽  
Substrate Concentrations ◽  
Chromatographic Isolation ◽  
Human Blood Platelets

SummaryThe LDH-isoenzymes of human blood platelets show a distinct predominance of the isoenzymes 2 and 3 upon chromatography on DEAE-cellulose. Small amounts of LDH-1 are also present, while only traces of LDH-4 and -5 can be detected.Enzyme kinetic investigations of the principal isoenzymes LDH-1, -2 and -3 clearly show that the differences in inhibition constants with pyruvate as substrate which are demonstrable at 25° largely disappear at 37°. On the other hand, the differences among the isoenzymes in their affinity for pyruvate and lactate as substrate as well as in with respect to the optimal substrate concentrations of pyruvate are more marked at 37° than at 25°. Also, the type of inhibition found with lactate as substrate is increasingly the expression of a higher order reaction in going from LDH-1 to LDH-3. A dependence of the LDH distribution pattern upon the metabolism of the cell is discussed. A comparison of our results with thrombocytes with those of other workers with erythrocytes and leucocytes makes it unlikely that the LDH pattern is directly dependent upon the existence of an oxidative metabolism. Rather, the redox potential of the cell could be of importance for the nature of the pattern of isoenzymes and for their differing kinetic properties.

Interaction of Vasopressin with Human Blood Platelets: Dependency on Mg2+

1986 ◽  
Vol 56 (03) ◽  
pp. 260-262 ◽  
Author(s):  
Isabella Roos ◽  
Fabrizia Ferracin ◽  
Alfred Pletscher
Keyword(s):  
Phosphatidic Acid ◽  
Human Blood ◽  
Arginine Vasopressin ◽  
Specific Binding ◽  
Blood Platelets ◽  
Bivalent Cations ◽  
Platelet Membranes ◽  
Maximal Rise ◽  
Human Blood Platelets ◽  
Stimulation Of

SummaryArginine-vasopressin (AVP) in the presence of Mg2+ but not in the absence of bivalent cations led to accumulation of [32P]-phosphatidic acid ([32P]-PA) in human blood platelets. Mg2+ also enhanced the specific binding of [3H]-AVP to intact platelets. The concentrations of the cation which enabled AVP to cause half maximal rise of [32P]-PA and those inducing half maximal [3H]-AVP-binding were of the same order. It is concluded that the stimulation of phosphatidyl inositide breakdown by AVP in presence of Mg2+ is at least partially due to a Mg2+-induced enhancement of specific AVP-binding to the platelet membranes.

Benzalkonium chloride interferes with energy production, secretion and morphology in human blood platelets

Platelets ◽  
1999 ◽  
Vol 10 (2) ◽  
pp. 97-104 ◽  
Author(s):  
Ø. Berg ◽  
A. M. Bakken ◽  
S. K. Steinsvåg ◽  
M. Farstad
Keyword(s):  
Human Blood ◽  
Benzalkonium Chloride ◽  
Energy Production ◽  
Blood Platelets ◽  
Human Blood Platelets
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