scholarly journals N 1 N 8-bis(γ-glutamyl)spermidine cross-linking in epidermal-cell envelopes. Comparison of cross-link levels in normal and psoriatic cell envelopes

1990 ◽  
Vol 271 (2) ◽  
pp. 305-308 ◽  
Author(s):  
N Martinet ◽  
S Beninati ◽  
T P Nigra ◽  
J E Folk
Keyword(s):  
Epidermal Cell ◽  
Skin Disease ◽  
Envelope Protein ◽  
Cell Envelope ◽  
Human Epidermis ◽  
Cross Linking ◽  
Cross Link ◽  
Gamma Glutamyl ◽  
Cell Envelopes ◽  
Isolated Cell

N1N8-Bis(gamma-glutamyl)spermidine was found in exhaustive proteolytic digests of isolated cell envelopes from human epidermis at levels comparable with those of epsilon-(gamma-glutamyl)lysine. Significantly higher than normal amounts of these compounds, particularly the bis(gamma-glutamyl)polyamine, were observed in envelopes from afflicted areas (scales) of psoriatic patients. These findings support the notions that N1N8-bis(gamma-glutamyl)spermidine, like epsilon-(gamma-glutamyl)lysine, functions in cell envelopes as an enzyme-generated protein cross-link and stabilizing force and that individuals with the chronic, recurrent skin disease, psoriasis, exhibit in involved epidermis abnormal cell-envelope-protein cross-linking.

Penetrability of a marine pseudomonad by inulin, sucrose, and glycerol and its relation to the mechanism of lysis

1970 ◽  
Vol 16 (2) ◽  
pp. 75-81 ◽  
Author(s):  
Francis L. A. Buckmire ◽  
Robert A. MacLeod
Keyword(s):  
Osmotic Pressure ◽  
Exchange Resin ◽  
Sucrose Solution ◽  
Cell Envelope ◽  
Sucrose Concentration ◽  
Ion Exchange Resin ◽  
Cell Preparation ◽  
Cell Envelopes ◽  
Almost All ◽  
Isolated Cell

Cells of a marine pseudomonad were prevented from lysing when suspended in a 0.15 M sucrose solution even after treatment of the sucrose with an ion exchange resin to remove contaminating trace elements. Isolated cell envelopes of the organism in concentrations of sucrose able to prevent lysis of the cells released non-dialyzable hexosamine-containing material into the suspending medium. This did not occur when the envelopes were suspended in concentrations of NaCl able to prevent cell lysis. Glycerol was found to occupy almost all the available fluid space in a packed cell preparation of the organism. Sucrose occupied less space than glycerol, and inulin the least. When the sucrose concentration was increased from 3 mM to 0.2 M, both the sucrose and inulin spaces increased. The results have been interpreted as indicating that sucrose prevents lysis by balancing the internal osmotic pressure of the cells, that the various layers of the cell envelope of the organism differ in their permeability to various solutes, and that the whole cell shrinks in solutions of high osmotic pressure.

scholarly journals Evidence for filaggrin as a component of the cell envelope of the newborn rat

1988 ◽  
Vol 253 (1) ◽  
pp. 153-160 ◽  
Author(s):  
S Richards ◽  
I R Scott ◽  
C R Harding ◽  
J E Liddell ◽  
G M Powell ◽  
...  
Keyword(s):  
Envelope Protein ◽  
Cell Envelope ◽  
Dependent Manner ◽  
Organ Cultures ◽  
Newborn Rat ◽  
Significant Component ◽  
In Vitro Systems ◽  
Cell Envelopes

A substrate of transglutaminase, specific to the epidermis, was identified, by fluorescent and radioactive labelling with the lysine analogues dansylcadaverine and [14C]putrescine respectively, in newborn-rat epidermal homogenates and whole-skin organ cultures. The labelled analogues were preferentially incorporated into the stratum-corneum protein filaggrin in a Ca2+-dependent manner in both ‘in vitro’ systems. When filaggrin was labelled in vivo with [3H]histidine and then incubated with rat epidermal preparations, the label was rendered SDS/thiol-insoluble. Incorporation of [3H]filaggrin into the insoluble envelope fraction was Ca2+-dependent and inhibited by EDTA and exogenous amines. Antisera to newborn-rat filaggrin cross-reacted with purified newborn-rat cell envelopes, and this reaction was blocked by adsorbing the antiserum with purified filaggrin. Quantification of the ‘envelope-bound’ filaggrin showed it to be a significant component, accounting for approx. 10% of the cell-envelope protein.

Does Fibrin Fragment D-Dimer Cross-Link With Fibrin Monomer?

1979 ◽  
Author(s):  
J.J. Franks ◽  
Betty C. Kao
Keyword(s):  
Factor Xiii ◽  
Tween 20 ◽  
Cross Linking ◽  
Cross Link ◽  
Irreversible Binding ◽  
Gamma Chain ◽  
Gamma Glutamyl ◽  
Fibrin Monomer ◽  
D Dimer

When 2 to 4 ng of radioiodinated human D-dimer (D-D) and 0.2 mg of carrier rabbit D-D in two ml of buffer were added to a .7x10 cm column containing 4 ml of agarose-linked rabbit, or human fibrin monomer, D-D was tightly bound. After a neutral buffer wash D-D was quantitatively eluted (97 to 99% recovery) with 6M urea (pH 8.6). Comparable recovery of unlabeled human D-D, 500 to 8000 ng, was achieved. Human D-D concentration was measured by radioimmunoassay with rabbit anti-human D-D serum. When labeled or unlabeled D-D was mixed with 2ml of serum or when serum from patients with high D-D levels was chromatographed, 40 to 70% of D-D was retained and could not be eluted even by washing the column with alkaline urea for 24 to 48 hours. Irreversible binding of D-D could not be prevented by adding DFP or Tween 20 or by pre-heating the carrier serum to 60°, but binding was completely prevented by 5 mM EDTA in the serum and eluting solutions. Let’s than 1% of labeled D-D remained on the affinity agarose. We have previously suggested that only one of two reciprocal gamma chain cross-linking sites is used when fibrinogen cross-linking takes place (S. Afr. J. Sci., 74:202, 1978). Activated factor XIII could utilize the spare site to form epsilon (gamma glutamyl)lysine bonds between insolubilized fibrin monomer and D-D.

scholarly journals The lipolytic activities of the isolated cell envelope fractions of baker's yeast

1970 ◽  
Vol 118 (5) ◽  
pp. 759-763 ◽  
Author(s):  
T. Nurminen ◽  
H. Suomalainen
Keyword(s):  
Plasma Membrane ◽  
Adenosine Triphosphatase ◽  
Cell Envelope ◽  
Baker’S Yeast ◽  
Baker's Yeast ◽  
Lipolytic Enzymes ◽  
Enzymic Digestion ◽  
Cell Envelopes ◽  
Isolated Cell ◽  
Lipid Components

1. The existence of phospholipase and lipase activities in the isolated cell envelopes of baker's yeast was demonstrated. 2. The content of phospholipase was found to be markedly higher than that of lipase. 3. After partial enzymic digestion of the isolated cell envelopes, the bulk of the lipolytic activities was recovered in the sedimentable preparations, which consisted of the fragments of the plasma membrane. 4. During repeated washings, the lipase was completely released from the cell envelopes, as were also the bulk of the lipid components and most of the Mg2+-dependent adenosine triphosphatase, an enzyme connected with the plasma membrane. The phospholipase was more firmly bound to the preparation but not so firmly as the external saccharase. 5. These results indicate that the lipolytic enzymes found in the cell envelopes are mostly located in the plasma membrane.

EXPERIMENTAL VALIDATION OF THE CHARLESBY AND HORIKX MODELS APPLIED TO DE-VULCANIZATION OF SULFUR AND PEROXIDE VULCANIZATES OF NR AND EPDM

2016 ◽  
Vol 89 (4) ◽  
pp. 671-688 ◽  
Author(s):  
M. A. L. Verbruggen ◽  
L. van der Does ◽  
W. K. Dierkes ◽  
J. W. M. Noordermeer
Keyword(s):  
Experimental Validation ◽  
Main Chain ◽  
Sol Gel ◽  
Chain Scission ◽  
Cross Linking ◽  
Cross Link ◽  
Practical Reality ◽  
Cross Links ◽  
The Cross ◽  
Theoretical Considerations

ABSTRACT The theoretical model developed by Charlesby to quantify the balance between cross-links creation of polymers and chain scission during radiation cross-linking and further modifications by Horikx to describe network breakdown from aging were merged to characterize the balance of both types of scission on the development of the sol content during de-vulcanization of rubber networks. There are, however, disturbing factors in these theoretical considerations vis-à-vis practical reality. Sulfur- and peroxide-cured NR and EPDM vulcanizates were de-vulcanized under conditions of selective cross-link and random main-chain scissions. Cross-link scission was obtained using thiol-amine reagents for selective cleavage of sulfur cross-links. Random main-chain scission was achieved by heating peroxide vulcanizates of NR with diphenyldisulfide, a method commonly employed for NR reclaiming. An important factor in the analyses of these experiments is the cross-linking index. Its value must be calculated using the sol fraction of the cross-linked network before de-vulcanization to obtain reliable results. The values for the cross-linking index calculated with sol-gel data before de-vulcanization appear to fit the experimentally determined modes of network scission during de-vulcanization very well. This study confirms that the treatment of de-vulcanization data with the merged Charlesby and Horikx models can be used satisfactorily to characterize the de-vulcanization of NR and EPDM vulcanizates.

scholarly journals Viscometric analysis of the gelation of Acanthamoeba extracts and purification of two gelation factors.

1980 ◽  
Vol 85 (2) ◽  
pp. 414-428 ◽  
Author(s):  
S D MacLean-Fletcher ◽  
T D Pollard
Keyword(s):  
Crude Extract ◽  
Cross Linking ◽  
Cross Link ◽  
Gelation Process ◽  
Optimum Ph ◽  
Kinetics Of ◽  
Low Shear

We have studied the kinetics of the gelation process that occurs upon warming cold extracts of Acanthamoeba using a low-shear falling ball assay. We find that the reaction has at least two steps, requires 0.5 mM ATP and 1.5 mM MgCl2, and is inhibited by micromolar Ca++. The optimum pH is 7.0 and temperature, 25 degrees-30 degrees C. The rate of the reaction is increased by cold preincubation with both MgCl2 and ATP. Nonhydrolyzable analogues of ATP will not substitute for ATP either in this "potentiation reaction" or in the gelation process. Either of two purified or any one of four partially purified Acanthamoeba proteins will cross-link purified actin to form a gel, but none can account for the dependence of the reaction in the crude extract on Mg-ATP or its regulation by Ca++. This suggests that the extract contains, in addition to actin-cross-linking proteins, factors dependent on Mg-ATP and Ca++ that regulate the gelation process.

Mechanical and structural consequences of associative dynamic cross-linking in acrylic diblock copolymers

2021 ◽  
Author(s):  
Jacob Ishibashi ◽  
Ian Pierce ◽  
Alice Chang ◽  
Aristotelis Zografos ◽  
Bassil El-Zaatari ◽  
...  
Keyword(s):  
Viscoelastic Properties ◽  
Diblock Copolymers ◽  
Microphase Separation ◽  
Network Connectivity ◽  
Ethyl Acrylate ◽  
Cross Linking ◽  
Cross Link ◽  
Block Polymers ◽  
Link Density ◽  
Cross Link Density

<p>The composition of low-T<sub>g</sub> <i>n</i>-butylacrylate-<i>block</i>-(acetoxyaceto)ethyl acrylate block polymers is investigated as a strategy to tune the properties of dynamically cross-linked vinylogous urethane vitrimers. As the proportion of the cross-linkable block is increased, the thermorheological properties, structure, and stress relaxation evolve in ways that cannot be explained by increasing cross-link density alone. Evidence is presented that network connectivity defects such as loops and dangling ends are increased by microphase separation. The thermomechanical and viscoelastic properties of block copolymer-derived vitrimers arise from the subtle interplay of microphase separation and network defects.</p><div><br></div><p></p>

Synthesis of amorphous low Tg polyesters with multiple COOH side groups and their utilization for elastomeric vitrimers based on post-polymerization cross-linking

2019 ◽  
Vol 10 (16) ◽  
pp. 2047-2056 ◽  
Author(s):  
Mikihiro Hayashi ◽  
Ryoto Yano ◽  
Akinori Takasu
Keyword(s):  
Cross Linking ◽  
Cross Link

Elastomeric vitrimer materials with tunable cross-link densities are prepared using cross-linking precursor polyesters with multiple COOH side groups in the presence of diepoxy cross-linkers and trans-esterification catalysts.

scholarly journals THE CELL ENVELOPES OF TWO EXTREMELY HALOPHILIC BACTERIA

1963 ◽  
Vol 18 (3) ◽  
pp. 681-689 ◽  
Author(s):  
A. D. Brown ◽  
C. D. Shorey
Keyword(s):  
Single Unit ◽  
Cell Envelope ◽  
Halophilic Bacteria ◽  
Layered Compound ◽  
Halobacterium Halobium ◽  
Chemical Analyses ◽  
Unit Membrane ◽  
Thin Sections ◽  
Whole Cells ◽  
Cell Envelopes

The cell envelope of Halobacterium halobium was seen in thin sections of permanganate-fixed cells to consist of one membrane. This membrane appeared mostly as a unit membrane but in a few preparations it resembled a 5-layered compound membrane. The cell envelope of Halobacterium salinarium at high resolution was always seen as a 5-layered structure different in appearance from the apparent compound membrane of H. halobium. The "envelopes" which were isolated in 12.5 per cent NaCl from each organism were indistinguishable from each other in the electron microscope and comprised, in each case, a single unit membrane with an over-all thickness of about 110 A. Some chemical analyses were made of isolated membranes after freeing them from salt by precipitating and washing with trichloroacetic acid. Such precipitated membranes consisted predominantly of protein, with little carbohydrate and no peptido-aminopolysaccharide (mucopeptide). Sectioned whole cells of H. halobium contained intracellular electron-opaque structures of unknown function.

scholarly journals RanGTP induces an effector gradient of XCTK2 and importin α/β for spindle microtubule cross-linking

2019 ◽  
Author(s):  
Stephanie C. Ems-McClung ◽  
Mackenzie Emch ◽  
Stephanie Zhang ◽  
Serena Mahnoor ◽  
Lesley N. Weaver ◽  
...  
Keyword(s):  
Cancer Cells ◽  
Spindle Assembly ◽  
Cross Linking ◽  
Tail Domain ◽  
Inhibitory Effects ◽  
Cross Link ◽  
Spindle Microtubule ◽  
Spindle Poles ◽  
Importin Α ◽  
Combined Actions

AbstractHigh RanGTP around chromatin is important for governing spindle assembly during meiosis and mitosis by releasing the inhibitory effects of importin α/β. Here we examine how the Ran gradient regulates Kinesin-14 function to control spindle organization. We show that Xenopus Kinesin-14, XCTK2, and importin α/β form an effector gradient, which is highest at the poles that diminishes toward the chromatin and is inverse of the RanGTP gradient. Importin α/β preferentially inhibit XCTK2 anti-parallel microtubule cross-linking and sliding by decreasing the microtubule affinity of the XCTK2 tail domain. This change in microtubule affinity enables RanGTP to target endogenous XCTK2 to the spindle. We propose that these combined actions of the Ran pathway are critical to promote Kinesin-14 parallel microtubule cross-linking at the spindle poles to cluster centrosomes in cancer cells. Furthermore, our work illustrates that RanGTP regulation in the spindle is not simply a switch, but rather generates effector gradients where RanGTP gradually tunes the activities of spindle assembly factors.SummaryEms-McClung et al. visualize a RanGTP effector gradient of association between XCTK2 and importin α/β in the spindle. The importins preferentially inhibit XCTK2-mediate anti-parallel microtubule cross-linking and sliding, which allows XCTK2 to cross-link parallel microtubules and help focus spindle poles.

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