Bio-inspired dynamic biomolecule assembling for fine regulation of protein activity

SummaryThe behavior of 125I-labeled recombinant hirudin towards the uninjured and de-endothelialized rabbit aorta wall has been studied in vitro and in vivo to determine its usefulness as an indicator of thrombin activity associated with the aorta wall. Thrombin adsorbed to either sulfopropyl-Sephadex or heparin-Sepharose bound >95% of 125I-r-hirudin and the complex remained bound to the matrix. Binding of 125I-r-hirudin to the exposed aorta subendothelium (intima-media) in vitro was increased substantially if the tissue was pre-treated with thrombin; the quantity of l25I-r-hirudin bound to the de-endothelialized intima-media (i.e. balloon-injured in vitro) correlated positively with the quantity of bound 131I-thrombin (p <0.01). Aortas balloon-injured in vivo were measured for thrombin release from, and binding of 125I-r-hirudin to, the de-endothelialized intimal surface in vitro; 125I-r-hirudin binding correlated with the amount of active thrombin released (p <0.001). Uptake of 125I-r-hirudin by the aorta wall in vivo was proportional to the uptake of 131I-fibrinogen (as an indicator of thrombin activity) before and after balloon injury. After 30 min in the circulation, specific 125I-r-hirudin binding to the uninjured and de-endo- thelialized (at 1.5 h after injury) aorta wall was equivalent to 3.4 (± 2.5) and 25.6 (±18.1) fmol of thrombin/cm2 of intima-media, respectively. Possibly, only hirudin-accessible, glycosaminoglycan-bound thrombin is measured in this way.

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Potato Inhibitors of Intrinsic Prothrombin Activators

Thrombosis and Haemostasis ◽

10.1055/s-0038-1651469 ◽

1975 ◽

Vol 34 (03) ◽

pp. 763-769

Author(s):

K Worowski

Keyword(s):

Protease Inhibitors ◽

No Inhibition ◽

Thrombin Activity ◽

Tissue Thromboplastin

SummaryThe potato protease inhibitors inhibit intrinsic prothrombin activators and trypsin activation of prothrombin. The inhibitors 5a and 5b are responsible for the intrinsic prothrombin activator inhibition. This inhibition is progressive. No inhibition by these inhibitors of tissue thromboplastin activation of prothrombin or thrombin activity was observed.

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The Ability of Thrombin Inhibitors to Reduce the Thrombin Activity Generated in Plasma on Extrinsic and Intrinsic Activation

Thrombosis and Haemostasis ◽

10.1055/s-0038-1655996 ◽

1997 ◽

Vol 77 (03) ◽

pp. 498-503 ◽

Cited By ~ 26

Author(s):

D Prasa ◽

L Svendsen ◽

J Stürzebecher

Keyword(s):

Active Site ◽

Thrombin Generation ◽

Anion Binding ◽

Thrombin Inhibitors ◽

Coagulation System ◽

Thrombin Activity ◽

Continuous Registration ◽

High Concentrations ◽

20 Nm ◽

Generation Test

SummaryIn a thrombin generation test with continuous registration of thrombin activity in plasma we studied the ability of a variety of thrombin inhibitors of different type and mechanism of action to influence the activity of thrombin after activation of the coagulation system. Depending on the inhibitor, the peak of thrombin activity is delayed and/or reduced.By blocking the active site of generated thrombin inhibitors cause a concentration dependent reduction of the thrombin peak and inhibit feed-back reactions of thrombin resulting in a delay of thrombin generation. Highly potent synthetic active-site directed inhibitors (Ki ≤ 20 nM) reduce the thrombin activity formed in plasma after extrinsic or intrinsic activation with the same efficiency (IC50 0.1 - 0.6 μM) as hirudin. The delay and reduction of thrombin generation by inhibitors of the anion-binding exosite 1 of thrombin is only attributed to an inhibition of feed-back reactions of thrombin. For a 50% reduction of thrombin activity in plasma by this type of inhibitors relatively high concentrations were determined.

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Deficiencies and Inhibitors of Thromboplastic Activity

Thrombosis and Haemostasis ◽

10.1055/s-0038-1655646 ◽

1966 ◽

Vol 16 (03/04) ◽

pp. 574-585

Author(s):

G. F Grannis ◽

L. A Kazal

Keyword(s):

Factor Viii ◽

Time Course ◽

Gamma Globulin ◽

Hemophilia A ◽

Naturally Occurring ◽

Thrombin Activity ◽

Activity Curve ◽

Lipoprotein Complex ◽

Thromboplastic Activity

SummaryThe effects of hereditary deficiencies of thromboplastic proteins (hemophilia A and B) on the time course of thrombin appearance and disappearance in plasma (the thrombin activity curve, TAC) were compared with the effects of a naturally occurring gamma-globulin inhibitor of thromboplastic activity and with an anti-thromboplastic activity derived from cephalin (phosphatidylserine-lipoprotein complex).Both inhibitors inhibit reactions involving the protein in which hemophilia A plasma is deficient (factor VIII).

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Supramolecular Assembly of U(IV) Clusters and Superatoms

10.26434/chemrxiv.11860065 ◽

2020 ◽

Author(s):

Ian Colliard ◽

Gregory Morrosin ◽

Hans-Conrad zur Loye ◽

May Nyman

Keyword(s):

Quantum Dots ◽

Supramolecular Assembly ◽

Emergent Properties ◽

Organic Media ◽

Body Centered Cubic ◽

Cluster Anions ◽

Charge Balance ◽

Interpenetrating Networks ◽

Hierarchical Assembly ◽

Two Parameters

Superatoms are nanometer-sized molecules or particles that can form ordered lattices, mimicking their atomic counterparts. Hierarchical assembly of superatoms gives rise to emergent properties in superlattices of quantum-dots, p-block clusters, and fullerenes. Here, we introduce a family of uranium-oxysulfate cluster anions whose hierarchical assembly in water is controlled by two parameters; acidity and the countercation. In acid, larger LnIII (Ln=La-Ho) link hexamer (U6) oxoclusters into body-centered cubic frameworks, while smaller LnIII (Ln=Er-Lu &Y) promote linking of fourteen U6-clusters into hollow superclusters (U84 superatoms). U84 assembles into superlattices including cubic-closest packed, body-centered cubic, and interpenetrating networks, bridged by interstitial countercations, and U6-clusters. Divalent transition metals (TM=MnII and ZnII), with no added acid, charge-balance and promote the fusion of 10 U6 and 10 U-monomers into a wheel–shaped cluster (U70). Dissolution of U70 in organic media reveals (by small-angle Xray scattering) that differing supramolecular assemblies are accessed, controlled by TM-linking of U70-clusters.

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Kinetic Control of Interpenetration in Fe-Biphenyl-4,4′-dicarboxylate MOFs by Coordination and Oxidation Modulation

10.26434/chemrxiv.7466633 ◽

2018 ◽

Author(s):

Dominic Bara ◽

Claire Wilson ◽

Max Mörtel ◽

Marat M. Khusniyarov ◽

ben slater ◽

...

Keyword(s):

Self Assembly ◽

Surface Areas ◽

Metal Precursors ◽

Additional Coordination ◽

Fine Control ◽

Multiple Alternative ◽

Metal Organic ◽

Dft Simulations ◽

High Valent ◽

And Control

Phase control in the self-assembly of metal-organic frameworks (MOFs) – materials wherein organic ligands connect metal ions or clusters into network solids with potential porosity – is often a case of trial and error. Judicious control over a number of synthetic variables is required to select for the desired topology and control features such as interpenetration and defectivity, which have significant impact on physical properties and application. Herein, we present a comprehensive investigation of self-assembly in the Fe-biphenyl-4,4'-dicarboxylate system, demonstrating that coordination modulation, the addition of competing ligands into solvothermal syntheses, can reliably tune between the kinetic product, non-interpenetrated MIL-88D(Fe), and the thermodynamic product, two-fold interpenetrated MIL-126(Fe). DFT simulations reveal that correlated disorder of the terminal anions on the metal clusters in the interpentrated phase results in H-bonding between adjacent nets and is the thermodynamic driving force for its formation. Coordination modulation slows self-assembly and therefore selects the thermodynamic product MIL-126(Fe), while offering fine control over defectivity, inducing mesoporosity, but electron microscopy shows the MIL-88D(Fe) phase persists in many samples despite not being evident in diffraction experiments, suggesting its presence accounts for the lower than predicted surface areas reported for samples to date. Interpenetration control is also demonstrated by utilizing the 2,2'-bipyridine-5,5'-dicarboxylate linker; DFT simulations show that it is energetically prohibitive for it to adopt the twisted conformation required to form the interpenetrated phase, and are confirmed by experimental data, although multiple alternative phases are identified due to additional coordination of the Fe cations to the N-donors of the ligand. Finally, we introduce oxidation modulation – the concept of using metal precursors in a different oxidation state to that found in the final MOF – as a further protocol to kinetically control self-assembly. Combining coordination and oxidation modulation allows the synthesis of pristine MIL-126(Fe) with BET surface areas close to the predicted maximum capacity for the first time, suggesting that combining the two may be a powerful methodology for the controlled self-assembly of high-valent MOFs.

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