scholarly journals MOLECULAR ANALYSIS OF THE MEMBRANE ATTACK MECHANISM OF COMPLEMENT

1972 ◽  
Vol 135 (3) ◽  
pp. 549-566 ◽  
Author(s):  
William P. Kolb ◽  
James A. Haxby ◽  
Carlos M. Arroyave ◽  
Hans J. Müller-Eberhard
Keyword(s):  
Binding Sites ◽  
Molecular Model ◽  
Cytolytic Activity ◽  
Cooperative Interaction ◽  
Molar Ratio ◽  
Human Complement ◽  
Complement Proteins ◽  
Molar Ratios ◽  
Molecular Arrangement ◽  
Hemolytic Effect

The molecular arrangement of the membrane attack mechanism of complement was explored. The molar ratios of the components within the C5-9 assembly on the target cell surface were determined using human complement proteins in highly purified and radiolabeled form. With the aid of monospecific complement antisera it was possible to probe the spatial relationships between the components of the assembly. C5 and C6, in the presence of C7, were bound to EAC1-3 in equimolar quantities irrespective of the amounts and the relative proportions of C5, C6, and C7 offered. The amount of C8 bound to EAC1-7 increased with input and at saturation of all C8 binding sites the molar ratio of bound C8/bound C5 approached 1.0. Uptake of C9 by EAC1-8 increased with input and at saturation of all C9 binding sites the molar ratio of bound C9/bound C8 became 6.0. However, calculations suggest that the binding of three C9 molecules to one C8 molecule is sufficient to achieve a full hemolytic effect. Evidence was obtained indicating that binding and hemolytic function of C9 depends upon cooperative interaction of multiple C9 molecules. Binding of C8 to EAC1-7 and the generation of hemolytic C8 sites were inhibited by antibody to either C5, C6, or C7. Uptake of C9 by EAC1-8 and the generation of hemolytic C9 sites were strongly inhibited by anti-C8 and to a lesser degree by anti-C5. Binding of C9 (but not hemolysis) was also reduced by antibody to C6 or C7. The data are consistent with the concept that the fully assembled membrane attack mechanism of complement consists of a decamolecular complex: a trimolecular arrangement composed of C5, C6, and C7 forms the binding site for one C8 molecule which in turn furnishes binding sites for six C9 molecules, saturation of three sites apparently being sufficient for expression of full cytolytic activity of the complex. This work made it possible to design a simple molecular model.

Relative Affinity of Plasmin for the α1-Macroglobulin, Cl Inactivator and α1-Antitrypsin Inhibitors

1975 ◽  
Author(s):  
Peter C. Harpel
Keyword(s):  
Complex Formation ◽  
Protease Inhibitors ◽  
Disulfide Bond ◽  
Light Chain ◽  
Binding Sites ◽  
Gel Electrophoresis ◽  
Molar Ratio ◽  
Molar Ratios ◽  
Relative Affinity ◽  
Quantitative Contribution

The quantitative contribution of three major plasma protease inhibitors in binding plasmin has been studied. Mixtures of plasmin and each of the purified inhibitors were analyzed by SDS-acrylamide gel electrophoresis. Plasmin remained bound to its inhibitors in the presence of SDS and urea. A 1 : 1 molar ratio for complex formation was established, and treatment of the complexes with a disulfide bond reducing agent showed that the light chain of plasmin contained the binding sites for both CĪ inactivator and α-antitrysin. Limited degradation of all three inhibitors by plasmin was observed, and the altered inhibitor remained complexed to the enzyme. The competitive binding of 125I plasmin to mixtures of these inhibitors was followed by sucrose density ultracentrifugation and by SDS-gel electrophoresis. In mixtures containing physiologic molar ratios of enzyme and inhibitors, over 80% of the bound plasmin was complexed to the α2-macroglobufui (α2M). No evidence for an exchange of plasmin between the inhibitors was obtained.

scholarly journals The Impact of AN Contribution on the Thermal Characteristics and Molecular Dynamics of Novel Acrylonitrile–Styrene–Styrene Sodium Sulfonate Terpolymers

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 420
Author(s):  
Hamud A. Altaleb ◽  
Abdullah M. Al-Enizi ◽  
Hany El-Hamshary ◽  
Sayed Z. Mohammady
Keyword(s):  
Molecular Dynamics ◽  
Glass Transition ◽  
Molecular Model ◽  
Thermal Characteristics ◽  
Molar Ratio ◽  
Thermal Stabilities ◽  
Sodium Sulfonate ◽  
Molar Ratios ◽  
Donor Acceptor ◽  
The Impact

We performed a free radical solution polymerization of new acrylonitrile (AN), styrene (St) and styrene sodium sulfonate (SSS) acceptor–donor acceptor monomer systems. The compositions and structures of the produced terpolymers were elucidated using CHNS elemental analysis, and Fourier transform infrared (FTIR) spectroscopies. Three terpolymers candidates were chosen for detailed thermal investigations, where the AN molar ratio varied almost threefold (from ~6.9% to ~17.4%) while the molar ratios of St and SSS varied slightly, at average values around 76.0% and 12.9%, respectively. The glass transition (Tg) values of the terpolymers were measured calorimetrically. In addition, thermal gravimetric analyses (TGA) of the samples were conducted in the temperature range from room temperature to 800 °C. All terpolymers exhibited a single Tg value, indicating random copolymerization of the monomeric species. TGA results revealed that variation of the AN molar ratio had a significant influence on the thermal stabilities of the terpolymers. The impact of AN contribution on the molecular dynamics of the glass transition in the terpolymers was explained quantitatively in a framework of a molecular model.

m-[o-(2-Chloro-5-Fluorosulfonylphenylureido)Phenoxybutoxy]Benzamidine: Affinity Labeling Reagent Which Can Identify Secondary Binding Sites of Coagulation Complement and Fibrinolytic Serine Proteases

1979 ◽  
Author(s):  
D Bing ◽  
D Robison ◽  
J Andrews ◽  
R Laura
Keyword(s):  
Binding Sites ◽  
Serine Proteases ◽  
Enzyme Inhibitor ◽  
Molecular Model ◽  
Factor Xa ◽  
Affinity Labeling ◽  
Catalytic Center ◽  
Inhibitor Complex ◽  
Polypeptide Chains ◽  
Kinetics Of

We have determined that m-[o-(2-chloro-5-fluorosulfonylphenylureido)phenoxybutoxy]benza-midine [mCP(PBA)-F] is an affinity labeling reagent which labels both polypeptide chains of thrombin, factor Xa, complement component CIS and plasmin. As this means it is reacting outside of the catalytic center, we have called this reagent an exo-site affinity labeling reagent. Progressive irreversible inhibition of these enzymes by this reagent is rapid (k1st 2.5-4.6 x 10-3sec-1), the kinetics of inactivation are consistent with inhibition proceding via formation of a specific enzyme-inhibitor complex analogous to a Michaelis-Menton complex (KL - 115-26 μM), and diisopropylfluorophosphate or p-amidino-phenylmethanesulfonyfluoride Prevent labeling by [3H]mCP(PBA)-F. A molecular model of mCP(PBA)-F shows that the reactive SO2F group can be 17 A from the cationic amidine. The data are consistent with the hypothesis that both peptide chains are required for the specific proteolytic activity exhibited by these proteases and that the peptide chain which does not contain the active site serine is close to the catalytic center. (Supported by NIH and AHA grants

scholarly journals Photocatalytic Reduction of CO2 to Methanol Using a Copper-Zirconia Imidazolate Framework

Catalysts ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 346
Author(s):  
Sonam Goyal ◽  
Maizatul Shima Shaharun ◽  
Ganaga Suriya Jayabal ◽  
Chong Fai Kait ◽  
Bawadi Abdullah ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Catalyst Support ◽  
Oxidation Potential ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Molar Ratios ◽  
Optimum Parameters ◽  
Reduction Of Co2 ◽  
Enhanced Yield

A set of novel photocatalysts, i.e., copper-zirconia imidazolate (CuZrIm) frameworks, were synthesized using different zirconia molar ratios (i.e., 0.5, 1, and 1.5 mmol). The photoreduction process of CO2 to methanol in a continuous-flow stirred photoreactor at pressure and temperature of 1 atm and 25 °C, respectively, was studied. The physicochemical properties of the synthesized catalysts were studied using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectroscopy. The highest methanol activity of 818.59 µmol/L.g was recorded when the CuZrIm1 catalyst with Cu/Zr/Im/NH4OH molar ratio of 2:1:4:2 (mmol/mmol/mmol/M) was employed. The enhanced yield is attributed to the presence of Cu2+ oxidation state and the uniformly dispersed active metals. The response surface methodology (RSM) was used to optimize the reaction parameters. The predicted results agreed well with the experimental ones with the correlation coefficient (R2) of 0.99. The optimization results showed that the highest methanol activity of 1054 µmol/L.g was recorded when the optimum parameters were employed, i.e., stirring rate (540 rpm), intensity of light (275 W/m2) and photocatalyst loading (1.3 g/L). The redox potential value for the CuZrIm1 shows that the reduction potential is −1.70 V and the oxidation potential is +1.28 V for the photoreduction of CO2 to methanol. The current work has established the potential utilization of the imidazolate framework as catalyst support for the photoreduction of CO2 to methanol.

scholarly journals Lipozyme 435-Mediated Synthesis of Xylose Oleate in Methyl Ethyl Ketone

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3317
Author(s):  
Maria Carolina Pereira Gonçalves ◽  
Jéssica Cristina Amaral ◽  
Roberto Fernandez-Lafuente ◽  
Ruy de Sousa Junior ◽  
Paulo Waldir Tardioli
Keyword(s):  
Oleic Acid ◽  
Methyl Ethyl Ketone ◽  
Molar Ratio ◽  
Methyl Ethyl ◽  
Sugar Ester ◽  
Molar Ratios ◽  
Emulsion Capacity ◽  
Ping Pong ◽  
Commercial Sugar ◽  
Repeated Use

In this paper, we have performed the Lipozyme 435-catalyzed synthesis of xylose oleate in methyl ethyl ketone (MEK) from xylose and oleic acid. The effects of substrates’ molar ratios, reaction temperature, reaction time on esterification rates, and Lipozyme 435 reuse were studied. Results showed that an excess of oleic acid (xylose: oleic acid molar ratio of 1:5) significantly favored the reaction, yielding 98% of xylose conversion and 31% oleic acid conversion after 24 h-reaction (mainly to xylose mono- and dioleate, as confirmed by mass spectrometry). The highest Lipozyme 435 activities occurred between 55 and 70 °C. The predicted Ping Pong Bi Bi kinetic model fitted very well to the experimental data and there was no evidence of inhibitions in the range assessed. The reaction product was purified and presented an emulsion capacity close to that of a commercial sugar ester detergent. Finally, the repeated use of Lipozyme 435 showed a reduction in the reaction yields (by 48 and 19% in the xylose and oleic acid conversions, respectively), after ten 12 h-cycles.

Appearance, corrosion properties, and leach resistance of spruce and pine wood treated with Mea modified micronized copper preservative (MCu)

Holzforschung ◽  
2014 ◽  
Vol 68 (4) ◽  
pp. 477-486 ◽  
Author(s):  
Myung Jae Lee ◽  
Sedric Pankras ◽  
Paul Cooper
Keyword(s):  
Wood Species ◽  
Wood Preservative ◽  
Molar Ratio ◽  
Corrosion Properties ◽  
Pine Wood ◽  
Molar Ratios ◽  
Copper Leaching ◽  
Mold Resistance ◽  
Refractory Wood

Abstract Canadian refractory wood species treated with micronized copper (MCu) wood preservative become mottled and streaky in appearance. To overcome this issue, the MCu system was modified by adding small amounts of monoethanolamine (Mea). The modified systems were evaluated to clarify the role of Mea in terms of leaching, corrosion, and mold resistance of MCu systems. The mottled and streaky surface on treated spruce was prevented at Mea/Cu molar ratios between 0.7 and 1.5. Copper leaching remained modest and was only slightly higher than that of MCu alone up to a Mea/Cu molar ratio of 1.2. However, adding even a small amount of Mea to the MCu formulation increased fastener corrosion compared with MCu. Protonated Mea increased as more Mea was added and was identified as the main corrosion-causing electrolyte in the system.

Hydrogen-bonded bent-core blue phase liquid crystal complexes containing various molar ratios of proton acceptors and donors

RSC Advances ◽  
2016 ◽  
Vol 6 (38) ◽  
pp. 32319-32327 ◽  
Author(s):  
Chun-Chieh Han ◽  
Yu-Chaing Chou ◽  
San-Yuan Chen ◽  
Hong-Cheu Lin
Keyword(s):  
Liquid Crystal ◽  
Chain Length ◽  
Alkyl Chain ◽  
Alkyl Chain Length ◽  
Chiral Center ◽  
Molar Ratio ◽  
Core Complex ◽  
Molar Ratios ◽  
Phase Liquid ◽  
Blue Phase

The molar ratio, alkyl chain length, lateral fluoro-substitution and the chiral center of H-bonded bent-core supramolecules would affect the BP ranges of BPLC complexes. H-bonded bent-core complex PIIIC9/AIIF* (3/7 mol mol−1) displayed the widest BPI range of ΔTBPI = 12 °C.

scholarly journals BrO/SO<sub>2</sub> molar ratios from scanning DOAS measurements in the NOVAC network

2013 ◽  
Vol 5 (2) ◽  
pp. 1845-1870 ◽  
Author(s):  
P. Lübcke ◽  
N. Bobrowski ◽  
S. Arellano ◽  
B. Galle ◽  
G. Garzón ◽  
...  
Keyword(s):  
Molar Ratio ◽  
Optical Absorption Spectroscopy ◽  
Short Term ◽  
Dynamic Changes ◽  
Volcanic System ◽  
Molar Ratios ◽  
Remote Sensing Technique ◽  
Field Campaigns ◽  
Term Field

Abstract. The molar ratio of BrO to SO2 is, like other halogen/sulphur ratios, a~possible precursor for dynamic changes in the shallow part of a volcanic system. While the predictive significance of the BrO/SO2 ratio has not been well constrained yet, it has the major advantage that this ratio can be readily measured using the remote-sensing technique Differential Optical Absorption Spectroscopy (DOAS) in the UV. While BrO/SO2 ratios have been measured during several short-term field campaigns this article presents an algorithm that can be used to obtain long-term time series of BrO/SO2 ratios from the scanning DOAS instruments of the Network for Observation of Volcanic and Atmospheric Change (NOVAC) or comparable networks. Parameters of the DOAS retrieval of both trace gases are given and the influence of co-adding spectra on the retrieval error will be investigated. Difficulties in the evaluation of spectroscopic data from monitoring instruments in volcanic environments and possible solutions are discussed. The new algorithm is demonstrated by evaluating data from the NOVAC scanning DOAS systems at Nevado del Ruiz, Colombia encompassing almost four years of measurements between November 2009 and end of June 2013. This dataset shows variations of the BrO/SO2 ratio several weeks prior to the eruption on 30 June 2012.

Structural characteristics of tetanolysin and its binding to lipid vesicles

1982 ◽  
Vol 152 (2) ◽  
pp. 888-892
Author(s):  
S Rottem ◽  
R M Cole ◽  
W H Habig ◽  
M F Barile ◽  
M C Hardegree
Keyword(s):  
Structural Characteristics ◽  
Lipid Vesicles ◽  
Molar Ratio ◽  
Molar Ratios ◽  
High Concentrations

Tetanolysin binding to lipid vesicles was found to depend on the molar ratio of cholesterol to phospholipid, being low in vesicles containing up to 20 mol% cholesterol and high in vesicles containing more than 33 mol%. High concentrations of purified tetanolysin preparations formed arc- and ring-shaped structures. The structures were not readily detectable in diluted preparations unless incubated with lipid vesicles containing high molar ratios of cholesterol to phospholipid. It is suggested that the toxin is concentrated on the vesicles to local concentrations high enough to form the arcs and rings.

Sign in / Sign up

Export Citation Format

Share Document