scholarly journals THE MECHANISM OF ACTION OF COLCHICINE

1973 ◽  
Vol 58 (3) ◽  
pp. 709-719 ◽  
Author(s):  
Leslie Wilson ◽  
Isaura Meza
Keyword(s):  
Binding Site ◽  
Vinca Alkaloid ◽  
Binding Activity ◽  
Temperature Dependent ◽  
Binding Reaction ◽  
First Order ◽  
Colchicine Binding Site ◽  
Thermal Depolymerization ◽  
Brain Tubulin ◽  
Vinblastine Sulfate

The thermal depolymerization procedure of Stephens (1970. J. Mol. Biol. 47:353) has been employed for solubilization of Strongylocentrotus purpuratus sperm tail outer doublet microtubules with the use of a buffer during solubilization which is of optimal pH and ionic strength for the preservation of colchicine binding activity of chick embryo brain tubulin. Colchicine binding values were corrected for first-order decay during heat solubilization at 50°C (t½ = 5.4 min) and incubation with colchicine at 37°C in the presence of vinblastine sulfate (t½ = 485 min). The colchicine binding properties of heat-solubilized outer doublet tubulin were qualitatively identical with those of other soluble forms of tubulin. The solubilized tubulin (mol wt, 115,000) bound 0.9 ± 0.2 mol of colchicine per mol of tubulin, with a binding constant of 6.3 x 105 liters/mol at 37°C. The colchicine binding reaction was both time and temperature dependent, and the binding of colchicine was prevented in a competitive manner by podophyllotoxin (Ki = 1.3 x 10-6 M). The first-order decay of colchicine binding activity was substantially decreased by the addition of the vinca alkaloids, vinblastine sulfate or vincristine sulfate, thus demonstrating the presence of a vinca alkaloid binding site(s) on the outer doublet tubulin. Tubulin contained within the assembled microtubules did not decay. Intact outer doublet microtubules bound less than 0.001 mol of colchicine per mol of tubulin contained in the microtubules, under conditions where soluble tubulin would have bound 1 mol of colchicine per mol of tubulin (saturating concentration of colchicine, no decay of colchicine binding activity). The presence of colchicine had no effect on the rate of solubilization of outer doublet microtubules during incubation at 37°C. Therefore, the colchicine binding site on tubulin is blocked (not available to bind colchicine) when the tubulin is in the assembled outer doublet microtubules.

scholarly journals Human somatotropin binding to rabbit kidney microsomal fraction

1981 ◽  
Vol 200 (2) ◽  
pp. 257-264 ◽  
Author(s):  
L P Roguin ◽  
S H Sánchez ◽  
J S Bonifacino ◽  
A C Paladini
Keyword(s):  
Binding Capacity ◽  
Specific Binding ◽  
Binding Activity ◽  
Rabbit Kidney ◽  
Scatchard Analysis ◽  
Temperature Dependent ◽  
Binding Reaction ◽  
Dissociation Equilibrium ◽  
Microsomal Membranes ◽  
Kidney Microsomes

Specific binding of 125I-labelled human somatotropin was demonstrated in microsomal membranes (microsomes) from rat and rabbit kidneys. Female rabbit kidney microsomes showed the highest binding activity and were used for further study. The association of 125I-labelled human somatotropin was time- and temperature-dependent and the binding reaction was reversible. Scatchard analysis of saturation data indicated a dissociation equilibrium constant, KD, of 56 pM and a binding capacity of 37 fmol per mg of protein. Similar results were obtained from competition experiments. Binding of 125I-labelled human somatotropin to the microsomes was specifically inhibited by hormones with lactogenic activity. The binding sites, as well as 125I-labelled human somatotropin, were not inactivated on incubation. Treatment of the microsomes with trypsin and chymotrypsin decreased the specific binding by over 90%. Preheating of the microsomes at 55 degrees C for 15 min abolished 50% of the specific binding activity.

Evidence for histidine residues in the immunoglobulin-binding site of human C1q

1983 ◽  
Vol 3 (2) ◽  
pp. 135-140 ◽  
Author(s):  
S. B. Easterbrook-Smith
Keyword(s):  
Binding Site ◽  
Binding Sites ◽  
Binding Activity ◽  
Ionic Interactions ◽  
Histidine Residues ◽  
First Order ◽  
First Order Kinetics ◽  
Inactivation Process ◽  
Immunoglobulin Binding ◽  
Modification Treatment

The immunoglobulin-binding activity of subcomponent Clq of human complement is lost following treatment with diethylpyrocarbonate; the inactivation showed first-order kinetics with respect to time and modifier concentration. Soluble IgG oligomers protected Clq against diethylpyrocarbonate modification. Treatment of modified Clq with hydroxylamine resulted in an 85% recovery of its ability to bind to aggregated immuno-globulin. The inactivation process was associated with modification of 12.1±0.7 histidine residues per Clq molecule. These data are consistent with the presence of histidine residues in the immunoglobulin-binding sites of Clq; these residues may participate in ionic interactions with the carboxyl groups known to be in the Clq binding site of IgG.

scholarly journals Taxol-induced rose microtubule polymerization in vitro and its inhibition by colchicine.

1984 ◽  
Vol 99 (1) ◽  
pp. 141-147 ◽  
Author(s):  
L C Morejohn ◽  
D E Fosket
Keyword(s):  
Binding Site ◽  
Cultured Cells ◽  
Critical Concentration ◽  
Relative Sensitivity ◽  
Mammalian Brain ◽  
Molar Ratios ◽  
Microtubule Polymerization ◽  
Colchicine Binding Site ◽  
Brain Tubulin

Tubulin was isolated from cultured cells of rose (Rosa, sp.cv. Paul's scarlet) by DEAE-Sephadex A50 chromatography, and the taxol-induced polymerization of microtubules in vitro was characterized at 24 degrees C by turbidity development, sedimentation analysis, and electron microscopy. Numerous, short microtubules were formed in the presence of taxol, and maximum levels of turbidity and polymer yield were obtained at approximately 2:1 molar ratios of taxol to tubulin. The critical concentration of rose tubulin for polymerization in saturating taxol was estimated to be 0.21 mg/ml. Colchicine inhibited the taxol-induced polymerization of tubulin as shown by sedimentation assays; however, much higher concentrations of colchicine were required for the inhibition of taxol-induced rose tubulin assembly than for inhibition of taxol-induced mammalian brain tubulin assembly. On the basis of the relative sensitivity of rose tubulin assembly to taxol and its insensitivity to colchicine, we propose that the taxol-binding site(s) on plant and animal tubulins have been more conserved over evolution than the colchicine-binding site(s).

scholarly journals Further characterization of the interaction between the cytoskeletal proteins talin and vinculin

2002 ◽  
Vol 362 (3) ◽  
pp. 761-768 ◽  
Author(s):  
Mark D. BASS ◽  
Bipin PATEL ◽  
Igor G. BARSUKOV ◽  
Ian J. FILLINGHAM ◽  
Robert MASON ◽  
...  
Keyword(s):  
Binding Site ◽  
Intramolecular Interaction ◽  
Binding Activity ◽  
Cytoskeletal Proteins ◽  
Actin Binding ◽  
Yeast Two Hybrid ◽  
Temperature Dependent ◽  
Two Hybrid ◽  
Actin Binding Site

The cytoskeletal protein talin, which is thought to couple integrins to F-actin, contains three binding sites (VBS1—VBS3) for vinculin, a protein implicated in the negative regulation of cell motility and whose activity is modulated by an intramolecular interaction between the vinculin head (Vh) and vinculin tail (Vt) domains. In the present study we show that recombinant talin polypeptides containing the three VBSs (VBS1, residues 498–636; VBS2, residues 727–965; and VBS3, residues 1943–2157) each bind tightly to the same or overlapping sites within vinculin1–258. A short synthetic talin VBS3 peptide (residues 1944–1969) was sufficient to inhibit binding of a 125I-labelled talin VBS3 polypeptide to vinculin1–258, and NMR spectroscopy confirmed that this peptide forms a 1:1 complex in slow exchange with vinculin1–258. Binding of the 125I-labelled VBS3 polypeptide was markedly temperature dependent, but was not inhibited by 1M salt or 10% (v/v) 2-methyl-2-propanol. Attempts to further define the talin-binding site within vinculin1–258 using a gel-blot assay were unsuccessful, but near maximal talin-binding activity was retained by a construct spanning vinculin residues 1–131 in a yeast two-hybrid assay. Interestingly, the talin VBS3 polypeptide was a potent inhibitor of the Vh—Vt interaction, and the VBS3 synthetic peptide was able to expose the actin-binding site in intact vinculin, which is otherwise masked by the Vh—Vt interaction. The results suggest that under certain conditions, talin may be an effective activator of vinculin.

Antithrombin-mediated Inhibition of Factor Vlla-Tissue Factor Complex by the Synthetic Pentasaccharide Representing the Heparin Binding Site to Antithrombin

1996 ◽  
Vol 76 (01) ◽  
pp. 005-008 ◽  
Author(s):  
Jean Claude Lormeau ◽  
Jean Pascal Herault ◽  
Jean Marc Herbert
Keyword(s):  
Binding Site ◽  
Tissue Factor ◽  
Residual Activity ◽  
Coagulation Factors ◽  
Heparin Binding ◽  
Experimental Conditions ◽  
First Order ◽  
Heparin Binding Site ◽  
Coagulant Activity

SummaryWe examined the effect of the synthetic pentasaccharide representing the minimal binding site of heparin to antithrombin on the antithrombin-mediated inactivation of factor Vila bound to tissue factor. This effect was compared to the effect of unfractionated heparin. Using purified recombinant human coagulation factors and either a clotting or an amidolytic assay for the determination of the residual activity of factor Vila, we showed that the pentasaccharide was an efficient antithrombin-dependent inhibitor of the coagulant activity of tissue factor-factor Vila complex. In our experimental conditions, assuming a mean MW of 14,000 for heparin, the molar pseudo-first order rate constants for ATIII-mediated FVIIa inhibition by ATIII-binding heparin and by the synthetic pentasaccharide were found to be similar with respective values of 104,000 ± 10,500 min-1 and 112,000 ± 12,000 min-1 (mean ± s.e.m., n = 3)

Synthesis, Anti-proliferative Evaluation, and Molecular Docking Studies of 3-(alkylthio)-5,6-diaryl-1,2,4-triazines as Tubulin Polymerization Inhibitors

2019 ◽  
Vol 16 (11) ◽  
pp. 1194-1201 ◽  
Author(s):  
Farhad Saravani ◽  
Ebrahim Saeedian Moghadam ◽  
Hafezeh Salehabadi ◽  
Seyednasser Ostad ◽  
Morteza Pirali Hamedani ◽  
...  
Keyword(s):  
Molecular Modeling ◽  
Cytotoxic Activity ◽  
Binding Site ◽  
Cell Line ◽  
Cell Lines ◽  
Tubulin Polymerization ◽  
Adenocarcinoma Cell Line ◽  
Adenocarcinoma Cell ◽  
Colchicine Binding Site ◽  
Anti Cancer

Background: The role of microtubules in cell division and signaling, intercellular transport, and mitosis has been well known. Hence, they have been targeted for several anti-cancer drugs. Methods: A series of 3-(alkylthio)-5,6-diphenyl-1,2,4-triazines were prepared and evaluated for their cytotoxic activities in vitro against three human cancer cell lines; human colon carcinoma cells HT-29, human breast adenocarcinoma cell line MCF-7, human Caucasian gastric adenocarcinoma cell line AGS as well as fibroblast cell line NIH-3T3 by MTT assay. Docking simulation was performed to insert these compounds into the crystal structure of tubulin at the colchicine binding site to determine a probable binding model. Compound 5d as the most active compound was selected for studying of microtubule disruption. Results: Compound 5d showed potent cytotoxic activity against all cell lines. The molecular modeling study revealed that some derivatives of triazine strongly bind to colchicine binding site. The tubulin polymerization assay kit showed that the cytotoxic activity of 5d may be related to inhibition of tubulin polymerization. Conclusion: The cytotoxicity and molecular modeling study of the synthesized compounds with their inhibition activity in tubulin polymerization demonstrate the potential of triazine derivatives for development of new anti-cancer agents.

Synthesis and tubulin interaction of thiocolchicines containing an isothiocyanato group. Synthesis of C(2)-deuterated and C(2)-14C-labeled 7-isothiocyanatodeacetamidothiocolchicine

1991 ◽  
Vol 56 (11) ◽  
pp. 2306-2312 ◽  
Author(s):  
Anjum Muzaffar ◽  
Ernest Hamel ◽  
Rouli Bai ◽  
Arnold Brossi
Keyword(s):  
Binding Site ◽  
Covalent Bond ◽  
Tubulin Polymerization ◽  
Low Concentration ◽  
Covalent Interaction ◽  
Isotope Label ◽  
Colchicine Binding Site

Synthesis of isothiocyanato substituted thiocolchicines XI - XIV is described. Introduction of an isotope label is demonstrated with the deuterated isothiocyanate XII and the 14C-labeled analog XIII. These isothiocyanates inhibit tubulin polymerization at low concentration. In addition, the 14C-labeled XIII forms covalent bond(s) with tubulin. Unfortunately, the covalent reaction while rapid, is not inhibited by preincubation of tubulin with colchicine. The covalent interaction of XIII with tubulin thus appears to be nonspecific, limiting its use as a marker of the colchicine binding site on tubulin.

scholarly journals Structural insights into targeting of the colchicine binding site by ELR510444 and parbendazole to achieve rational drug design

RSC Advances ◽  
2021 ◽  
Vol 11 (31) ◽  
pp. 18938-18944
Author(s):  
Jia-Hong Lei ◽  
Ling-Ling Ma ◽  
Jing-Hong Xian ◽  
Hai Chen ◽  
Jian-Jian Zhou ◽  
...  
Keyword(s):  
Drug Design ◽  
Binding Site ◽  
Crystal Structures ◽  
Rational Drug Design ◽  
Colchicine Binding Site ◽  
Rational Drug ◽  
Structural Insights

Crystal structures of tubulin complexed with ELR510444 and parbendazole facilitate the design of novel colchicine binding site inhibitors.

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