Fibrinogen C-terminal peptidic sequences (Haptides) modulate fibrin polymerization

2004 ◽  
Vol 91 (01) ◽  
pp. 43-51 ◽  
Author(s):  
Matti Ben-Moshe ◽  
Sholomo Magdassi ◽  
Raphael Gorodetsky ◽  
Gerard Marx
Keyword(s):  
Platelet Aggregation ◽  
Cell Attachment ◽  
Fibrin Clot ◽  
Nano Particles ◽  
Amino Acid Residues ◽  
Fibrin Gel ◽  
Transmission Microscopy ◽  
Average Size ◽  
Β Chain ◽  
Positively Charged

SummaryWe previously described synthetic peptides of 19-21 amino acid residues, homologous to the C-termini of fibrinogen Fib340 and Fib420, from the β-chain (Cβ), the extended αE chain (CαE) and near the end of the γ-chain (preCγ) which elicited attachment (haptotactic) responses from mesenchymal cells. We named these haptotactic peptides -Haptides. The effects of Haptides on fibrin clot formation was evaluated and their possible effects on platelet aggregation was examined. The Haptides Cβ, CαE and preCγ, (2-10 μM) increased fibrin clot turbidity and also decreased thrombin-induced clotting time. Higher concentrations (>120 μM of Cβ or preCγ) induced fibrinogen precipitation even without thrombin. These precipitates exhibited different ultrastructure from thrombin-induced fibrin by scanning and transmission microscopy. C-terminal peptides of the other fibrinogen chains exerted no such effects. Sepharose beads covalently coated with either whole fibrinogen or Haptides (SB-Fib or SB-Haptide) highly adsorbed free FITCHaptides. In aqueous solution, Haptides formed nano-particles with average size of ∼150nm in diameter. We suggest that such positively charged aggregates could serve to nucleate and accelerate fibrin gel formation. These results also indicate that Cβ and preCγ sequences within fibrin(ogen) participate in the docking and condensation of fibrin(ogen) during its assembly into a fibrin clot. By contrast, Haptides up to 100µM did not bind to platelets, and had no effect on platelet aggregation. Our findings highlight the roles of the C-terminal sequences of the β and γ chains in fibrin(ogen) polymerization as well as in cell attachment.

Influence of nascent polypeptide positive charges on translation dynamics

2020 ◽  
Vol 477 (15) ◽  
pp. 2921-2934
Author(s):  
Rodrigo D. Requião ◽  
Géssica C. Barros ◽  
Tatiana Domitrovic ◽  
Fernando L. Palhano
Keyword(s):  
Mrna Decay ◽  
Translation Termination ◽  
Published Data ◽  
Translation Efficiency ◽  
Amino Acid Residues ◽  
High Concentration ◽  
Strong Argument ◽  
Translation Arrest ◽  
Exit Tunnel ◽  
Positively Charged

Protein segments with a high concentration of positively charged amino acid residues are often used in reporter constructs designed to activate ribosomal mRNA/protein decay pathways, such as those involving nonstop mRNA decay (NSD), no-go mRNA decay (NGD) and the ribosome quality control (RQC) complex. It has been proposed that the electrostatic interaction of the positively charged nascent peptide with the negatively charged ribosomal exit tunnel leads to translation arrest. When stalled long enough, the translation process is terminated with the degradation of the transcript and an incomplete protein. Although early experiments made a strong argument for this mechanism, other features associated with positively charged reporters, such as codon bias and mRNA and protein structure, have emerged as potent inducers of ribosome stalling. We carefully reviewed the published data on the protein and mRNA expression of artificial constructs with diverse compositions as assessed in different organisms. We concluded that, although polybasic sequences generally lead to lower translation efficiency, it appears that an aggravating factor, such as a nonoptimal codon composition, is necessary to cause translation termination events.

Properties of Fibrinogen Cleaved by Jararhagin, a Metalloproteinase from the Venom of Bothrops jararaca

1994 ◽  
Vol 72 (02) ◽  
pp. 244-249 ◽  
Author(s):  
Aura S Kamiguti ◽  
Joseph R Slupsky ◽  
Mirko Zuzel ◽  
Charles R M Hay
Keyword(s):  
Platelet Aggregation ◽  
Platelet Function ◽  
Fibrin Clot ◽  
Clot Formation ◽  
Human Fibrinogen ◽  
Activated Platelets ◽  
Bothrops Jararaca ◽  
Platelet Binding ◽  
Fibrin Monomers ◽  
Fibrinogen Molecule

SummaryHaemorrhagic metalloproteinases from Bothrops jararaca and other venoms degrade vessel-wall and plasma proteins involved in platelet plug and fibrin clot formation. These enzymes also cause proteolytic digestion of fibrinogen which has been suggested to cause defective platelet function. Fibrinogen degradation by jararhagin, a metalloproteinase from B. jararaca, and the effect of jararhagin fibrinogenolysis on both platelet aggregation and fibrin clot formation were investigated. Jararhagin was found to cleave human fibrinogen in the C-terminal region of the Aα-chain giving rise to a 285-290 kDa fibrinogen molecule lacking the Aα-chain RGD 572-574 platelet-binding site. Platelet binding and aggregation of ADP-activated platelets is unaffected by this modification. This indicates that the lost site is not essential for platelet aggregation, and that the remaining platelet binding sites located in the N-terminal portion of Aα chains (RGD 95-97) and the C-terminal of γ chains (dodecapeptide 400-411) are unaffected by jararhagin-digestion of fibrinogen. Fibrin clot formation with thrombin of this remnant fibrinogen molecule was defective, with poor polymerization of fibrin monomers but normal release of FPA. The abnormal polymerization could be explained by the loss of one of the two complementary polymerization sites required for side-by-side association of fibrin protofibrils. Jararhagin-induced inhibition of platelet function, an important cause of haemorrhage in envenomed patients, is not caused by proteolysis of fibrinogen, as had been thought, and the mechanism remains to be elucidated.

scholarly journals Species-Specific Regulation of TRPM2 by PI(4,5)P2 via the Membrane Interfacial Cavity

2021 ◽  
Vol 22 (9) ◽  
pp. 4637
Author(s):  
Daniel Barth ◽  
Andreas Lückhoff ◽  
Frank J. P. Kühn
Keyword(s):  
Amino Acid Residues ◽  
Hek 293 ◽  
Complete Inactivation ◽  
293 Cells ◽  
Activation Mechanisms ◽  
Specific Regulation ◽  
Species Specific ◽  
Inside Out ◽  
Positively Charged

The human apoptosis channel TRPM2 is stimulated by intracellular ADR-ribose and calcium. Recent studies show pronounced species-specific activation mechanisms. Our aim was to analyse the functional effect of phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2), commonly referred to as PIP2, on different TRPM2 orthologues. Moreover, we wished to identify the interaction site between TRPM2 and PIP2. We demonstrate a crucial role of PIP2, in the activation of TRPM2 orthologues of man, zebrafish, and sea anemone. Utilizing inside-out patch clamp recordings of HEK-293 cells transfected with TRPM2, differential effects of PIP2 that were dependent on the species variant became apparent. While depletion of PIP2 via polylysine uniformly caused complete inactivation of TRPM2, restoration of channel activity by artificial PIP2 differed widely. Human TRPM2 was the least sensitive species variant, making it the most susceptible one for regulation by changes in intramembranous PIP2 content. Furthermore, mutations of highly conserved positively charged amino acid residues in the membrane interfacial cavity reduced the PIP2 sensitivity in all three TRPM2 orthologues to varying degrees. We conclude that the membrane interfacial cavity acts as a uniform PIP2 binding site of TRPM2, facilitating channel activation in the presence of ADPR and Ca2+ in a species-specific manner.

Block of Human Heart hH1 Sodium Channels by the Enantiomers of Bupivacaine

2000 ◽  
Vol 93 (4) ◽  
pp. 1022-1033 ◽  
Author(s):  
Carla Nau ◽  
Sho-Ya Wang ◽  
Gary R. Strichartz ◽  
Ging Kuo Wang
Keyword(s):  
Human Heart ◽  
Point Mutations ◽  
Cell Voltage ◽  
Site Directed Mutagenesis ◽  
Na Channel ◽  
Amino Acid Residues ◽  
Na Channels ◽  
State Dependent ◽  
Positively Charged

Background S(-)-bupivacaine reportedly exhibits lower cardiotoxicity but similar local anesthetic potency compared with R(+)-bupivacaine. The bupivacaine binding site in human heart (hH1) Na+ channels has not been studied to date. The authors investigated the interaction of bupivacaine enantiomers with hH1 Na+ channels, assessed the contribution of putatively relevant residues to binding, and compared the intrinsic affinities to another isoform, the rat skeletal muscle (mu1) Na+ channel. Methods Human heart and mu1 Na+ channel alpha subunits were transiently expressed in HEK293t cells and investigated during whole cell voltage-clamp conditions. Using site-directed mutagenesis, the authors created point mutations at positions hH1-F1760, hH1-N1765, hH1-Y1767, and hH1-N406 by introducing the positively charged lysine (K) or the negatively charged aspartic acid (D) and studied their influence on state-dependent block by bupivacaine enantiomers. Results Inactivated hH1 Na+ channels displayed a weak stereoselectivity with a stereopotency ratio (+/-) of 1.5. In mutations hH1-F1760K and hH1-N1765K, bupivacaine affinity of inactivated channels was reduced by approximately 20- to 40-fold, in mutation hH1-N406K by approximately sevenfold, and in mutations hH1-Y1767K and hH1-Y1767D by approximately twofold to threefold. Changes in recovery of inactivated mutant channels from block paralleled those of inactivated channel affinity. Inactivated hH1 Na+ channels exhibited a slightly higher intrinsic affinity than mu1 Na+ channels. Conclusions Differences in bupivacaine stereoselectivity and intrinsic affinity between hH1 and mu1 Na+ channels are small and most likely of minor clinical relevance. Amino acid residues in positions hH1-F1760, hH1-N1765, and hH1-N406 may contribute to binding of bupivacaine enantiomers in hH1 Na+ channels, whereas the role of hH1-Y1767 remains unclear.

Effects of Fe3O4 Nano Particles Addition in High Temperature Superconductor YBa2Cu3O7-δ

2012 ◽  
Vol 501 ◽  
pp. 309-313 ◽  
Author(s):  
Siti Nurdalila Abd-Ghani ◽  
Roslan Abd-Shukor ◽  
Wei Kong
Keyword(s):  
Transport Properties ◽  
Solid State Reaction Method ◽  
Nano Particles ◽  
Magnetic Impurities ◽  
Oxide Powders ◽  
Nano Fe3o4 ◽  
Activated Flux ◽  
Average Size ◽  
Increasing Temperature ◽  
Magnetic Nano Particles

The effects of nano particles Fe3O4 addition on the superconducting and transport properties of YBa2Cu3O7-δ (YBCO) were studied. YBa2Cu3O7-δ superconductor powders were prepared by using high purity oxide powders via solid state reaction method. Nano Fe3O4 with 0.01 – 0.05 wt.% with average size 28 nm was added into YBCO. The transition temperatures (Tc) of the samples were measured by using four point probe method. The critical current (Ic) of the samples has been determined by using the 1 μV/cm criterion from 30 – 77 K. Sample with 0.02 wt.% nano Fe3O4 showed the highest Tc at 87 K. It is interesting to note the same sample also exhibited the highest Jc at 77 K up to 1683 mA/cm2. Nano Fe3O4 has acted as effective flux pinning centers in YBCO. A small amount of nano particles Fe3O4 addition has successfully improved the superconducting and transport properties of YBCO. The excessive addition of nano Fe3O4 (> 0.02 wt.%) suppressed the Tc and Jc. Overall, Jc decreases with increasing temperature (30 – 77 K) as a consequence of thermally activated flux creep. Magnetic impurities normally suppress superconductivity. However, by adding magnetic nano particles, current carrying capacity of superconductors YBCO was enhanced significantly.

scholarly journals Positively charged amino acid residues located similarly in sea anemone and scorpion toxins

1994 ◽  
Vol 269 (24) ◽  
pp. 16785-16788
Author(s):  
E.P. Loret ◽  
R.M. del Valle ◽  
P. Mansuelle ◽  
F. Sampieri ◽  
H. Rochat
Keyword(s):  
Amino Acid ◽  
Sea Anemone ◽  
Amino Acid Residues ◽  
Scorpion Toxins ◽  
Positively Charged

scholarly journals Sequence and Structure of Human Rhinoviruses Reveal the Basis of Receptor Discrimination

2003 ◽  
Vol 77 (12) ◽  
pp. 6923-6930 ◽  
Author(s):  
Marketa Vlasak ◽  
Soile Blomqvist ◽  
Tapani Hovi ◽  
Elizabeth Hewat ◽  
Dieter Blaas
Keyword(s):  
Low Density Lipoprotein ◽  
Three Dimensional ◽  
Density Lipoprotein ◽  
Major Group ◽  
Amino Acid Residues ◽  
X Ray ◽  
Vldl Receptor ◽  
Capsid Protein Vp1 ◽  
Three Dimensional Models ◽  
Positively Charged

ABSTRACT The sequences of the capsid protein VP1 of all minor receptor group human rhinoviruses were determined. A phylogenetic analysis revealed that minor group HRVs were not more related to each other than to the nine major group HRVs whose sequences are known. Examination of the surface exposed amino acid residues of HRV1A and HRV2, whose X-ray structures are available, and that of three-dimensional models computed for the remaining eight minor group HRVs indicated a pattern of positively charged residues within the region, which, in HRV2, was shown to be the binding site of the very-low-density lipoprotein (VLDL) receptor. A lysine in the HI loop of VP1 (K224 in HRV2) is strictly conserved within the minor group. It lies in the middle of the footprint of a single repeat of the VLDL receptor on HRV2. Major group virus serotypes exhibit mostly negative charges at the corresponding positions and do not bind the negatively charged VLDL receptor, presumably because of charge repulsion.

Involvement of class II β-chain amino acid residues 85 and 86 in T-cell allorecognition

1990 ◽  
Vol 27 (3) ◽  
pp. 240-253 ◽  
Author(s):  
David D. Eckels ◽  
Mary J. Geiger ◽  
Thomas W. Sell ◽  
Jack A. Gorski
Keyword(s):  
Amino Acid ◽  
T Cell ◽  
Class Ii ◽  
Amino Acid Residues ◽  
Β Chain

scholarly journals A novel missense mutation in the FGB g. 3354 T>A (p. Y41N), Fibrinogen Caracas VIII

2011 ◽  
Vol 105 (04) ◽  
pp. 627-634 ◽  
Author(s):  
Héctor Rojas ◽  
Michael Meyer ◽  
Oscar Castillo ◽  
Arlette De Sáez Ruiz ◽  
John Weisel ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Fibrin Clot ◽  
Polymerization Process ◽  
Confocal Laser ◽  
Fibrinogen Concentration ◽  
Thrombin Time ◽  
Normal Range ◽  
Amino Terminal ◽  
Fibrin Network ◽  
Β Chain

SummaryA novel dysfibrinogenaemia with a replacement of Tyr by Asn at Bβ41 has been discovered (fibrinogen Caracas VIII). An asymptomatic 39-year-old male was diagnosed as having dysfibrinogenaemia due to a mildly prolonged thrombin time (+ 5.8 seconds); his fibrinogen concentration was in the low normal range, both by Clauss and gravimetric determination, 1.9 g/l and 2.1 g/l, respectively. The plasma polymerization process was slightly impaired, characterised by a mildly prolonged lag time and a slightly increased final turbidity. Permeation through the patients´ clots was dramatically increased, with the Darcy constant around four times greater than that of the control (22 ± 2 x10–9 cm2 compared to 6 ± 0.5 x10–9 cm2 in controls). The plasma fibrin structure of the patient, by scanning electron microscopy, featured a mesh composed of thick fibres (148 ± 50 nm vs. 120 ± 31 nm in controls, p<0.05) and larger pores than those of the control fibrin clot. The viscoelastic properties of the clot from the patient were also altered, as the storage modulus (G‘, 310 ± 30) was much lower than in the control (831 ± 111) (p ≤0.005). The interaction of the fibrin clot with a monolayer of human microvascular endothelial cells, by confocal laser microscopy, revealed that the patients´ fibrin network had less interaction with the cells. These results demonstrate the significance of the amino terminal end of the β chain of fibrin in the polymerisation process and its consequences on the clot organisation on the surface of endothelial cells.

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