Aqueous Gel Formation of a Synthetic Peptide Derived from the β-Sheet Domain of Platelet Factor-4

2002 ◽  
Vol 3 (6) ◽  
pp. 1225-1232 ◽  
Author(s):  
Nathan A. Lockwood ◽  
Robert van Tankeren ◽  
Kevin H. Mayo
Keyword(s):  
Synthetic Peptide ◽  
Platelet Factor 4 ◽  
Gel Formation ◽  
Platelet Factor ◽  
Β Sheet

scholarly journals Backbone and side-chain dynamics of residues in a partially folded β-sheet peptide from platelet factor-4

1997 ◽  
Vol 6 (2) ◽  
pp. 355-363 ◽  
Author(s):  
Vladimir A. Daragan ◽  
Elena E. Ilyina ◽  
Cynthia G. Fields ◽  
Gregg B. Fields ◽  
Kevin H. Mayo
Keyword(s):  
Platelet Factor 4 ◽  
Side Chain ◽  
Platelet Factor ◽  
Chain Dynamics ◽  
Β Sheet ◽  
Side Chain Dynamics

Relation Of Heparin Binding And Conformation In PF4 AND LA-PF4 (βTG)

1981 ◽  
Author(s):  
John C Holt ◽  
Marek Kloczewiak ◽  
Daniel A Walz ◽  
Boguslaw Rucinski ◽  
Stefan Niewiarowski
Keyword(s):  
Amino Acid ◽  
Disulfide Bonds ◽  
Amino Acid Sequences ◽  
Platelet Factor 4 ◽  
Heparin Binding ◽  
Platelet Factor ◽  
Significant Difference ◽  
Lysine Residues ◽  
Α Helix ◽  
Β Sheet

Platelet factor 4 (PF4) and low affinity platelet factor 4 (LA-PF4) are platelet-specific secreted proteins that bind to heparin. β-thromboglobulin (βTG) appears to be derived from LA-PF4 by proteolysis of four NH2-terminal residues. PF4 and LA-PF4 (βTG) show 50% sequence homology including four cysteine residues and two pairs of lysine residues near the C00H-terminus which are believed to be responsible for heparin binding. Despite these similarities, the two proteins have markedly different affinities for heparin. We have sought a structural interpretation of this difference by predicting the conformations of 0TG, LA-PF4 and PF4. First, the proportion of residues in α-helical, β-sheet and unordered conformations was estimated from circular dichroism measurements. The results for PF4 and LA-PF4 were experimentally identical, namely 16% α-helix and 20% β-sheet. These values were then applied as experimental constraints in the prediction of the secondary structure of PF4 and LA-PF4 based on their amino acid sequences. This was done by a computer program which compared local amino acid sequence (each residue and 8 residues on either side) with the conformation of similar sequences in 25 proteins of known structure. With the further constraint of the two disulfide bonds in each molecule, models were constructed representing the overall folding of the polypeptide chains. The only significant difference between the two proteins was in the COOH-terminal region of the chains. The models suggest that the lower affinity of LA-PF4 (and βTG) for heparin may result from steric hindrance by the longer and more negatively charged COOH-terminal segments of these molecules compared with PF4.

Half-Life of Platelet Factor 4 (PF-4) in Plasma and Platelets from Macaca Mulatta

1977 ◽  
Vol 37 (01) ◽  
pp. 073-080 ◽  
Author(s):  
Knut Gjesdal ◽  
Duncan S. Pepper
Keyword(s):  
Macaca Mulatta ◽  
Half Life ◽  
Human Platelet ◽  
Gel Filtration ◽  
Platelet Factor 4 ◽  
Active Protein ◽  
Platelet Factor ◽  
Membrane Bound

SummaryHuman platelet factor 4 (PF-4) showed a reaction of complete identity with PF-4 from Macaca mulatta when tested against rabbit anti-human-PF-4. Such immunoglobulin was used for quantitative precipitation of in vivo labelled PF-4 in monkey serum. The results suggest that the active protein had an intra-platelet half-life of about 21 hours. In vitro 125I-labelled human PF-4 was injected intravenously into two monkeys and isolated by immuno-precipita-tion from platelet-poor plasma and from platelets disrupted after gel-filtration. Plasma PF-4 was found to have a half-life of 7 to 11 hours. Some of the labelled PF-4 was associated with platelets and this fraction had a rapid initial disappearance rate and a subsequent half-life close to that of plasma PF-4. The results are compatible with the hypothesis that granular PF-4 belongs to a separate compartment, whereas membrane-bound PF-4 and plasma PF-4 may interchange.

Beta-Thromboglobulin (βtg) and Platelet Factor 4 (PF4) in Patients with Myeloproliferative Diseases

1994 ◽  
Vol 72 (03) ◽  
pp. 484-485
Author(s):  
Fabrizio Fabris ◽  
Guido Luzzatto ◽  
Maria Luigia Randi ◽  
Giuseppe Cella
Keyword(s):  
Platelet Factor 4 ◽  
Platelet Factor ◽  
Myeloproliferative Diseases

Release of Platelet Factor 4 in Vivo during Intravascular Coagulation and in Thrombotic States

1968 ◽  
Vol 19 (03/04) ◽  
pp. 578-583 ◽  
Author(s):  
R Farbiszewski ◽  
S Niewiarowski ◽  
K Worowski ◽  
B Lipiński
Keyword(s):  
Coronary Thrombosis ◽  
Laboratory Diagnosis ◽  
Tolerance Test ◽  
Platelet Factor 4 ◽  
Thrombin Time ◽  
Significant Elevation ◽  
Platelet Factor ◽  
Thrombotic Diseases ◽  
Disseminated Intravascular Clotting

SummaryPlatelet factor 4 released from platelets into the circulating blood was determined using both the heparin thrombin time and paracoagulation methods. It has been found that thrombin injected intravenously into rabbits releases large amounts of this factor. Infusion of plasmin does not release this factor and this finding may be of importance for the differential diagnosis between disseminated intravascular clotting and primary fibrinolysis. PF4 is not released during the hyper coagulable condition induced by HgCl2 intoxication. Only small amounts of this factor are released after contact factor infusion.A significant elevation of extraplatelet PF4 was found in 23 patients with fresh coronary thrombosis and in 9 patients with thrombophlebitis and thromboembolic complications.The significance of the above findings for the pathogenesis, treatment and laboratory diagnosis of thrombotic diseases with particular reference to heparin tolerance test is discussed.

Neutralization of Antithrombin VI (Fibrinogen Breakdown Products) with Platelet Antiheparin Factor (Platelet Factor 4)*

1965 ◽  
Vol 14 (03/04) ◽  
pp. 490-499 ◽  
Author(s):  
S Niewiarowski ◽  
R Farbiszewski ◽  
A Popławski
Keyword(s):  
Zinc Acetate ◽  
Antithrombin Iii ◽  
Platelet Factor 4 ◽  
Breakdown Product ◽  
Platelet Factor ◽  
Chromatography Column ◽  
Antiheparin Activity

SummaryIt has been found that fibrinogen breakdown product – antithrombin VI – is neutralized by the purified preparation of platelet factor 4, obtained by means of zinc acetate precipitation and DEAE chromatography column. It has been suggested that antiheparin activity of platelet factor 4 and its ability to neutralize antithrombin VI may be related to the same protein.The purified preparation of platelet factor 4 does not influence the fibrinogen – fibrin conversion by thrombin. This means that platelet factor 2 and platelet factor 4 are not the same substance.Crude platelet extracts neutralize antithrombin III and V. However, the purified product did not interferes with the action of these antithrombins.

Coagulation Disorders in Thrombocythaemia, a Study of Seven Cases

1962 ◽  
Vol 07 (01) ◽  
pp. 114-128 ◽  
Author(s):  
Stefan Niewiarowski ◽  
Halina Zywicka ◽  
Zbigniew Latałło
Keyword(s):  
Liver Parenchyma ◽  
Platelet Factor 4 ◽  
Coagulation System ◽  
Severe Bleeding ◽  
Clotting Factors ◽  
Platelet Factor ◽  
Antiheparin Activity ◽  
Thromboplastic Activity ◽  
Bleeding Episodes ◽  
Routine Coagulation

SummaryThe blood coagulation system has been studied in 7 patients with thrombocythaemia. 4 of these patients had thrombocythaemia after splenectomy, 2 of them had thrombocythaemia associated with myeloid leukemia, and 1 thrombocythaemia associated with polycythaemia. Severe bleeding episodes were noted in 5 cases, 2 patients had only mild bleeding symptoms.Each patient was examined several times. The period of observations varied from 2 months to 3 years. Platelet count varied from 350 000 to 3 800 000 per mm3.Bleeding time and tourniquet test were normal in all cases. Routine coagulation and fibrinolysis studies did not reveale characteristic abnormalities in plasma clotting factors. A decrease of prothrombin complex components was observed in 4 cases. This disturbance was due to the coexisting injury of liver parenchyma or myeloid changes but not to an increase of platelets or to the abnormalities in the platelet system.An increase of antiheparin activity was found in the plasma of 4 patients. This activity is probably due to the escape of platelet factor 4 from destroyed or qualitatively changed platelets into plasma.Platelet clotting factors were investigated in isolated platelet suspensions, A significant decrease of platelet factor 1 was observed in all patients and a decrease of platelet factor 4 in 5 patients. In 2 cases platelet factor 4 increased. Platelet thromboplastic activity showed a great variety of disturbances in conformity with other workers observations.Recent views on the pathogenesis of bleedings in thrombocythaemia are discussed. On the basis of their own investigations the authors suggest that the significant disturbances of platelet function may contribute to the development of bleeding, and that the increase of antiheparin activity in plasma may produce hypercoagulability and favorize the formation of thrombi.

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