Formation of boundary lubricating films during friction in synthetic oil modified with naphthalene derivatives

2021 ◽  
pp. 77-80
Author(s):  
Keyword(s):  
Complex Formation ◽  
Complex Compounds ◽  
Naphthalene Derivatives ◽  
Form Complex ◽  
Synthetic Oil ◽  
Boundary Film ◽  
Dioctyl Sebacate ◽  
Lubricating Properties

The influence of additives of naphthalene derivatives on the formation of boundary lubricating layers during friction in a dioctyl sebacate synthetic oil is considered. It is determined, that the activity of the additives is determined by the presence of acidic groups in their molecules and the ability to form complex compounds with metals. Keywords: boundary film, dioctyl sebacate, naphthalene derivatives, complex formation, lubricating properties [email protected]

scholarly journals Structural Basis of Complex Formation Between Mitochondrial Anion Channel VDAC1 and Hexokinase-II

2020 ◽  
Author(s):  
Nandan Haloi ◽  
Po-Chao Wen ◽  
Qunlii Cheng ◽  
Meiying Yang ◽  
Gayathri Natarajan ◽  
...  
Keyword(s):  
Complex Formation ◽  
Hybrid Approach ◽  
Md Simulations ◽  
Structural Basis ◽  
Stable Complex ◽  
Binary Complex ◽  
Hexokinase Ii ◽  
Insertion Depth ◽  
Form Complex ◽  
Membrane Bound

ABSTRACTComplex formation between hexokinase-II (HKII) and the mitochondrial channel VDAC1 plays a crucial role in regulating cell growth and survival; however, structural details of this complex remain elusive. We hypothesize that a conserved, hydrophobic helix (H-anchor) of HKII first inserts into the outer membrane of mitochondria (OMM) and then interacts with VDAC1 on the cytosolic leaflet of OMM to form a binary complex. To systematically investigate this process, we adopted a hybrid approach: 1) the membrane binding of HKII was first described with molecular dynamics (MD) simulations employing a membrane mimetic model with enhanced lipid diffusion, then 2) the resulting membrane-bound HKII was used to form complex with VDAC1 in millisecond-scale Brownian dynamics (BD) simulations. We show that H-anchor inserts its first 10 residues into the membrane, substantiating previous experimental findings. The insertion depth of the H-anchor was used to derive positional restraints in subsequent BD simulations to preserve the membrane-bound pose of HKII during the formation of the HKII/VDAC1 binary complex. Multiple BD-derived structural models were further refined with MD simulations, resulting in one stable complex. A major feature in the complex is the partial (not complete) blockade of VDAC1’s permeation pathway by HKII, a result supported by our comparative electrophysiological measurements of the channel in the presence and absence of HKII. Additionally, we showed how VDAC1 phosphorylation disrupts HKII binding, a feature that is verified by our electrophysiology recordings and have implications in mitochondria-mediated cell death.

Platelet-agglutinating protein P37 from a thrombotic thrombocytopenic purpura plasma forms a complex with human immunoglobulin G

Blood ◽  
1988 ◽  
Vol 71 (2) ◽  
pp. 299-304 ◽  
Author(s):  
FA Siddiqui ◽  
EC Lian
Keyword(s):  
Complex Formation ◽  
Thrombotic Thrombocytopenic Purpura ◽  
Fluid Phase ◽  
Enzyme Linked Immunosorbent Assay ◽  
Thrombocytopenic Purpura ◽  
Form Complex ◽  
Specific Igg ◽  
Sepharose 4B

Abstract We have previously reported the purification of a 37-kd platelet- agglutinating protein (PAP p37) from the plasma of a patient with thrombotic thrombocytopenic purpura (TTP) that was shown to be present in a subset of TTP patients. The platelet agglutination induced by PAP p37 has been shown to be inhibited by IgG from normal human adults and the same TTP patient after recovery. To elucidate the mechanism of inhibition of IgG, the interaction between PAP p37 and IgG was studied. The complex formation was demonstrated by the binding of fluid-phase IgG from normal adults and the same TTP patient after recovery to adsorbed PAP by using an enzyme-linked immunosorbent assay. The binding was specific, concentration dependent, and saturable. IgG purified from a 5-month-old baby and the same TTP patient during active disease did not form complex with PAP p37. The IgG covalently cross-linked to Sepharose 4B bound 125I-PAP p37 but not 125I-fibrinogen. Sucrose density gradient ultracentrifugation of a mixture of 125I-PAP p37 and IgG also revealed the fluid-phase complex formation with a sedimentation value of 19S. Complexes of molecular weight ranging from 180,000 to over 350,000 daltons were also detected by molecular sieve chromatography. The IgG that was bound to PAP p37 conjugated to Sepharose 4B inhibited the agglutination of washed platelets induced by TTP plasma containing PAP p37, whereas the IgG that was not bound to PAP p37 did not have a significant inhibitory effect. The complex formation between PAP p37 and specific IgG is likely to account for the in vitro inhibition of TTP plasma-induced agglutination and, at least partly, the in vivo successful treatment with specific IgG-containing normal plasma.

scholarly journals Apolipoprotein E structural requirements for the formation of SDS-stable complexes with β-amyloid-(1–40): the role of salt bridges

2002 ◽  
Vol 366 (1) ◽  
pp. 273-279 ◽  
Author(s):  
Nicholas M. BENTLEY ◽  
Mary Jo LaDU ◽  
Chandrika RAJAN ◽  
Godfrey S. GETZ ◽  
Catherine A. REARDON
Keyword(s):  
Complex Formation ◽  
Apolipoprotein E ◽  
Salt Bridge ◽  
Cysteine Residue ◽  
Stable Complex ◽  
Salt Bridges ◽  
Form Complex ◽  
Human Apolipoprotein ◽  
Toxic Species ◽  
Β Amyloid

Of the three major isoforms of human apolipoprotein E (apoE), apoE4 is a risk factor for the development of Alzheimer's disease. Among possible neurologically relevant differences in the properties of apoE3 and apoE4 is the fact that apoE3 forms an SDS-stable complex with β-amyloid-(1–40) (Aβ40) with greater avidity than does apoE4. This interaction may sequester potentially toxic species of Aβ or facilitate clearance. To understand more about this difference, we examined whether differences in salt bridges between apoE domains influence the capacity of apoE isoforms to form complexes with Aβ. In apoE3 there is a salt bridge between Arg-61 and Asp-65, while in apoE4 there are salt bridges between Arg-61 and Glu-255, and Arg-112 and Glu-109. Mutation of position 112, which is Cys in apoE3 and Arg in apoE4, to Ala or Lys abolished complex formation, while mutant apoE with Ser at this position retained the capacity to form complex. Substituting Ala for Glu-109 had no effect on the ability of either apoE4 or apoE3 to form complexes. On the other hand, substitution of Thr for Arg-61 in apoE3 abolished, and truncation of apoE3 at position 201 substantially lowered, but did not abolish, complex formation. Neither of these mutations within apoE4 had any affect on its complex formation with Aβ. These results suggest that the nature of the cysteine residue in apoE3 and interactions between the N-terminal and C-terminal domains of human apoE are important for the ability of apoE3 to form an SDS-stable complex with Aβ40.

Effect of structure and composition of solid carbon coatings of steel parts on the lubricating properties of synthetic oil

2013 ◽  
Vol 34 (5) ◽  
pp. 358-361 ◽  
Author(s):  
I. A. Buyanovskii ◽  
V. A. Levchenko ◽  
A. N. Bol’shakov ◽  
M. N. Zelenskaya ◽  
Z. V. Ignatieva ◽  
...  
Keyword(s):  
Solid Carbon ◽  
Carbon Coatings ◽  
Synthetic Oil ◽  
Effect Of Structure ◽  
Lubricating Properties

scholarly journals Methods for extraction of mercury compounds from coal in Ukraine

2019 ◽  
pp. 7-11
Author(s):  
S. D. Boruk ◽  
A. I. Kushnіr ◽  
O. S. Boruk
Keyword(s):  
Fine Particles ◽  
Complex Compounds ◽  
Hot Water ◽  
Raw Material ◽  
Complexing Agent ◽  
Form Complex ◽  
Mercury Compounds ◽  
Dispersed Particles ◽  
Volcanic Processes ◽  
Degree Of Extraction

The ways of prevention of environmental pollution by coal-containing mercury compounds are investigated in the paper. Coal mercury compounds are harmful and toxic impurities. In coal, the mercury is in the form of sulfides and mercury-containing organic compounds. Considerable amounts of native mercury and cinnabar are also recorded. The content of the mercury in terms of metal in the Donbass coal ranges from 0.01 to 1000 g / t. The highest concentrations of mercury compounds are due to hydrothermal and volcanic processes. In Donbass coal, the content of mercury compounds is on average 5 to 10 times greater than the background compared to other coal basins. The most common form of mercury compounds in coal are impurities in sulfide minerals. The content of mercury compounds in pyrite is two orders of magnitude higher than in the organic coal component. It is established that the bulk of the mercury compounds are contained in fine particles. The maximum content is fixed in a fraction of 0.1 - 15 microns. Thus, it can be assumed that the mercury compounds are predominantly contained in the mineral component of coal, which is more intensively ground. It is shown that washing with hot water and the complexing agent solution results in a decrease in the content of mercury compounds in the coal feedstock. The washing solutions become turbid, and this suggests that the mercury compounds are flushed out with fine particles. The increase in the degree of extraction of compounds of the mercury when applying the complexing solution is due to the ability of aurintricarboxylic acid to form complex compounds with the mercury ions. It can be assumed that in this case chemisorption occurs with the formation of complex compounds of the chelate structure on the surface of the particles, followed by dispersion of the particles of the dispersed phase. It was found that washing of the dispersed coal raw material is accompanied by weight loss. This indicates that the mercury compounds are leached from the coal in the form of dispersed particles. Waste sludge is to be disposed of with further disposal.

scholarly journals Antithrombin-III-Hamilton, Ala 382 to Thr: an antithrombin-III variant that acts as a substrate but not an inhibitor of alpha-thrombin and factor Xa

Blood ◽  
1991 ◽  
Vol 77 (10) ◽  
pp. 2185-2189
Author(s):  
RC Austin ◽  
RA Rachubinski ◽  
FA Ofosu ◽  
MA Blajchman
Keyword(s):  
Complex Formation ◽  
Serine Proteases ◽  
Antithrombin Iii ◽  
Factor Xa ◽  
Biological Behavior ◽  
Form Complex ◽  
Free System ◽  
Reactive Center ◽  
Sds Page ◽  
At Iii

Antithrombin-III-Hamilton has been shown to be a structural variant of antithrombin-III (AT-III) with normal heparin affinity but impaired protease inhibitory activity. The molecular defect of AT-III-Hamilton is the substitution of Thr for Ala at amino acid residue 382. The plasma of affected individuals contains approximately equal quantities of normal AT-III and AT-III-Hamilton. When AT-III was isolated from the plasma of the propositus by heparin-Sepharose chromatography, it had identical mobility on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) to normal plasma-derived AT-III, under both reducing and nonreducing conditions. However, the AT-III-Hamilton species, separated from the propositus' normal AT-III by a combination of heparin-Sepharose and thrombin-Sepharose chromatography, had increased mobility on reductive SDS-PAGE compared with AT-III from the propositus isolated by heparin-Sepharose chromatography alone. Under nonreducing conditions this AT-III-Hamilton species had decreased mobility compared with AT-III from the propositus (or normal AT-III) isolated only by heparin-Sepharose chromatography. When incubated with either human alpha-thrombin or human factor Xa, this AT-III-Hamilton species was unreactive. Approximately 50% of the AT-III from the propositus isolated by heparin-Sepharose chromatography, when incubated with either human alpha-thrombin or factor Xa, did not form complex but was cleaved, presumably at the reactive center Arg393-Ser394. To further substantiate the biological behavior of this variant, AT-III- Hamilton polypeptides were synthesized in a cell-free system. This recombinantly produced AT-III-Hamilton, when incubated with either human alpha-thrombin or factor Xa, was cleaved by both these proteases, but did not show any complex formation. The results indicate that AT- III-Hamilton does not form a stable covalent inhibitory complex with these serine proteases but can be cleaved at the reactive center. Thus, the inhibition of serine proteases by their natural inhibitors (the serpins) involves at least two separate, but interrelated events; hydrolysis at the reactive center followed by complex formation. AT-III- Hamilton is capable of only the first of these events.

scholarly journals Water-Soluble Substances of Arglabin

2020 ◽  
Vol 22 (3) ◽  
pp. 205
Author(s):  
S.M. Adekenov ◽  
А.N. Zhabayeva ◽  
G.М. Baisarov
Keyword(s):  
Complex Formation ◽  
Sesquiterpene Lactone ◽  
Glycyrrhizic Acid ◽  
Water Solubility ◽  
Magnesium Carbonate ◽  
Complex Compounds ◽  
Disodium Salt ◽  
Water Soluble ◽  
Mechanochemical Treatment ◽  
Complexing Agents

The article discusses the results of a study of the water solubility of natural sesquiterpene lactone arglabin, in particular, its ability to complex formation with complexing agents polyvinylpyrrolidone, the disodium salt of glycyrrhizic acid, magnesium carbonate. Mechanocomposites with polyvinylpyrrolidone and disodium salt of glycyrrhizic acid, which have increased water solubility, were obtained by the method of mechanochemical treatment of arglabin native. At the same time, the best result of dissolution in water is achieved by a two-hour treatment with polyvinylpyrrolidone and with disodium salt of glycyrrhizic acid. The water solubility of complex compounds of arglabin with polyvinylpyrrolidone increases by 4.61 times, and with disodium salt of glycyrrhizic acid by 4.42 times.

The V–Cr–Mn Group

2010 ◽  
Author(s):  
George K. Schweitzer ◽  
Lester L. Pesterfield
Keyword(s):  
Coordination Number ◽  
Oxidation State ◽  
Complex Compounds ◽  
Oxidation States ◽  
Complex Ions ◽  
Form Complex ◽  
The Third ◽  
Ph Values ◽  
Transition Series ◽  
Strong Action

The three elements to be treated in this chapter (V, Cr, Mn) are the third, fourth, and fifth members of the first transition series. The first two members (Sc, Ti) have been treated in previous chapters (Chapters 12 and 13). The ten elements of this first transition series (Sc through Zn) are characterized by electron activity in the 3d–4s levels. All elements in the 3d transition series are metals, and many of their compounds tend to be colored as a result of unpaired electrons. Most of the elements have a strong tendency to form complex ions due to participation of the d electrons in bonding. Since both the 4s and the 3d electrons are active, most of the elements show a considerable variety of oxidation states (Sc and Zn being exceptions). For the first five (Sc through Mn), the maximum oxidation number is the total number of electrons in the 4s and 3d levels. Complexing is often so strong that the most stable oxidation state for simple compounds may differ from that for complex compounds. a. E–pH diagram. The E–pH diagram in Figure 14.1 shows V in oxidation states of 0, II, III, IV, and V. This diagram, which involves vanadium at 10−3.0 M is somewhat oversimplified in that there are some isopolyanions present in the 4–6 pH regions. The prevalence of isopolyanions increases as the V concentration increases. This is illustrated in Figure 14.2 which has V at 10−1.0 M. Further, the cations V+2, V+3, VO+2, and VO2+ are probably aquated to satisfy a coordination number of six, and the V(OH)3 may actually be hydrated V2O3. Note that the soluble solution chemistries of V(IV) and V(V) are dominated by the VO+2 and VO2+ complex ions. Three of these cations (III, IV, V) are subject to hydrolysis, the processes setting in around pH values of just under 3, 3, and 2. The E–pH diagram indicates that elemental V is very active, but a thin coat of oxide protects it from all except strong action.

scholarly journals Antithrombin-III-Hamilton, Ala 382 to Thr: an antithrombin-III variant that acts as a substrate but not an inhibitor of alpha-thrombin and factor Xa

Blood ◽  
1991 ◽  
Vol 77 (10) ◽  
pp. 2185-2189 ◽  
Author(s):  
RC Austin ◽  
RA Rachubinski ◽  
FA Ofosu ◽  
MA Blajchman
Keyword(s):  
Complex Formation ◽  
Serine Proteases ◽  
Antithrombin Iii ◽  
Factor Xa ◽  
Biological Behavior ◽  
Form Complex ◽  
Free System ◽  
Reactive Center ◽  
Sds Page ◽  
At Iii

Abstract Antithrombin-III-Hamilton has been shown to be a structural variant of antithrombin-III (AT-III) with normal heparin affinity but impaired protease inhibitory activity. The molecular defect of AT-III-Hamilton is the substitution of Thr for Ala at amino acid residue 382. The plasma of affected individuals contains approximately equal quantities of normal AT-III and AT-III-Hamilton. When AT-III was isolated from the plasma of the propositus by heparin-Sepharose chromatography, it had identical mobility on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) to normal plasma-derived AT-III, under both reducing and nonreducing conditions. However, the AT-III-Hamilton species, separated from the propositus' normal AT-III by a combination of heparin-Sepharose and thrombin-Sepharose chromatography, had increased mobility on reductive SDS-PAGE compared with AT-III from the propositus isolated by heparin-Sepharose chromatography alone. Under nonreducing conditions this AT-III-Hamilton species had decreased mobility compared with AT-III from the propositus (or normal AT-III) isolated only by heparin-Sepharose chromatography. When incubated with either human alpha-thrombin or human factor Xa, this AT-III-Hamilton species was unreactive. Approximately 50% of the AT-III from the propositus isolated by heparin-Sepharose chromatography, when incubated with either human alpha-thrombin or factor Xa, did not form complex but was cleaved, presumably at the reactive center Arg393-Ser394. To further substantiate the biological behavior of this variant, AT-III- Hamilton polypeptides were synthesized in a cell-free system. This recombinantly produced AT-III-Hamilton, when incubated with either human alpha-thrombin or factor Xa, was cleaved by both these proteases, but did not show any complex formation. The results indicate that AT- III-Hamilton does not form a stable covalent inhibitory complex with these serine proteases but can be cleaved at the reactive center. Thus, the inhibition of serine proteases by their natural inhibitors (the serpins) involves at least two separate, but interrelated events; hydrolysis at the reactive center followed by complex formation. AT-III- Hamilton is capable of only the first of these events.

Sign in / Sign up

Export Citation Format

Share Document