scholarly journals Chemistry of collagen cross-links: glucose-mediated covalent cross-linking of type-IV collagen in lens capsules

1993 ◽  
Vol 296 (2) ◽  
pp. 489-496 ◽  
Author(s):  
A J Bailey ◽  
T J Sims ◽  
N C Avery ◽  
C A Miles
Keyword(s):  
Type Iv Collagen ◽  
Cross Linking ◽  
Mechanical And Thermal Properties ◽  
Maximum Strain ◽  
Scanning Calorimetry ◽  
Melting Temperatures ◽  
Type Iv ◽  
Collagen Molecules ◽  
Cross Links

The incubation of lens capsules with glucose in vitro resulted in changes in the mechanical and thermal properties of type-IV collagen consistent with increased cross-linking. Differential scanning calorimetry (d.s.c.) of fresh lens capsules showed two major peaks at melting temperatures Tm 1 and Tm 2 at approx. 54 degrees C and 90 degrees C, which can be attributed to the denaturation of the triple helix and 7S domains respectively. Glycosylation of lens capsules in vitro for 24 weeks caused an increase in Tm 1 from 54 degrees C to 61 degrees C, while non-glycosylated, control incubated capsules increased to a Tm 1 of 57 degrees C. The higher temperature required to denature the type-IV collagen after incubation in vitro suggested increased intermolecular cross-linking. Glycosylated lens capsules were more brittle than fresh samples, breaking at a maximum strain of 36.8 +/- 1.8% compared with 75.6 +/- 6.3% for the fresh samples. The stress at maximum strain (or ‘strength’) was dramatically reduced from 12.0 to 4.7 N.mm.mg-1 after glycosylation in vitro. The increased constraints within the system leading to loss of strength and increased brittleness suggested not only the presence of more cross-links but a difference in the location of these cross-links compared with the natural lysyl-aldehyde-derived cross-links. The chemical nature of the fluorescent glucose-derived cross-link following glycosylation was determined as pentosidine, at a concentration of 1 pentosidine molecule per 600 collagen molecules after 24 weeks incubation. Pentosidine was also determined in the lens capsules obtained from uncontrolled diabetics at a level of about 1 per 100 collagen molecules. The concentration of these pentosidine cross-links is far too small to account for the observed changes in the thermal and mechanical properties following incubation in vitro, clearly indicating that another as yet undefined, but apparently more important cross-linking mechanism mediated by glucose is taking place.

scholarly journals Inhibition of laminin self-assembly and interaction with type IV collagen by antibodies to the terminal domain of the long arm.

1986 ◽  
Vol 103 (5) ◽  
pp. 1689-1697 ◽  
Author(s):  
A S Charonis ◽  
E C Tsilibary ◽  
T Saku ◽  
H Furthmayr
Keyword(s):  
Self Assembly ◽  
Binding Sites ◽  
Type Iv Collagen ◽  
Specific Interaction ◽  
Basement Membranes ◽  
Complex Domain ◽  
Peptide Fragment ◽  
Type Iv ◽  
Collagen Molecules

Laminin is a major glycoprotein of the basement membrane. Although its precise localization and orientation within this structure is unknown, it is presumably anchored to other macromolecules such as type IV collagen or proteoheparan sulfate. In vitro, laminin has the ability to self-assemble and to bind to type IV collagen molecules at distinct sites. To identify more precisely the domains of the complex, cross-shaped laminin molecule that are involved in these interactions, images of laminin-laminin dimers and laminin-type IV collagen complexes obtained by the rotary shadowing method were analyzed. We observed that the complex domain at the end of the long arm of laminin is predominantly involved in these interactions. By using Fab fragments of antibodies specific for a peptide fragment derived from this complex domain, it is shown that laminin self-assembly is inhibited in their presence, as measured by turbidity and by electron microscopy. In addition, these antibodies inhibit the specific interaction of laminin with type IV collagen. These data suggest that the complex domain at the end of the long arm of laminin contains binding sites of potential importance for the assembly of basement membranes.

scholarly journals Structural and Thermo-Mechanical Properties of Poly(ε-caprolactone) Modified by Various Peroxide Initiators

Polymers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1101 ◽  
Author(s):  
Przybysz ◽  
Hejna ◽  
Haponiuk ◽  
Formela
Keyword(s):  
Mechanical Properties ◽  
Differential Scanning Calorimetry ◽  
Cross Linking ◽  
Mechanical And Thermal Properties ◽  
Dicumyl Peroxide ◽  
Organic Peroxides ◽  
Reactive Processing ◽  
Scanning Calorimetry ◽  
Melting Temperatures ◽  
Gel Fraction

The modification of poly(ε-caprolactone) (PCL) was successfully conducted during reactive processing in the presence of dicumyl peroxide (DCP) or di-(2-tert-butyl-peroxyisopropyl)-benzene (BIB). The peroxide initiators were applied in the various amounts of 0.5 or 1.0 pbw (part by weight) into the PCL matrix. The effects of the initiator type and its concentration on the structure and mechanical and thermal properties of PCL were investigated. To achieve a detailed and proper explication of this phenomenon, the decomposition and melting temperatures of DCP and BIB initiators were measured by differential scanning calorimetry. The conjecture of the branching or cross-linking of PCL structure via used peroxides was studied by gel fraction content measurement. Modification in the presence of BIB in PCL was found to effectively increase gel fraction. The result showed that the cross-linking of PCL started at a low content of BIB, while PCL modified by high DCP content was only partially cross-linked or branched. PCL branching and cross-linking were found to have a significant impact on the mechanical properties of PCL. However, the effect of used initiators on poly(ε-caprolactone) properties strongly depended on their structure and content. The obtained results indicated that, for the modification towards cross-linking/branching of PCL structure by using organic peroxides, the best mechanical properties were achieved for PCL modified by 0.5 pbw BIB or 1.0 pbw DCP, while the PCL modified by 1.0 pbw BIB possessed poor mechanical properties, as it was related to over cross-linking.

scholarly journals Cross-linking in type IV collagen

1984 ◽  
Vol 218 (3) ◽  
pp. 713-723 ◽  
Author(s):  
A J Bailey ◽  
T J Sims ◽  
N Light
Keyword(s):  
Basement Membrane ◽  
Type Iv Collagen ◽  
Collagen Molecule ◽  
Cross Linking ◽  
Type Iv ◽  
Long Form ◽  
Basement Membrane Collagen ◽  
Cross Links ◽  
Membrane Collagen ◽  
Salt Fractionation

Type IV collagen could not be extracted from human placenta using 6M-urea containing 10mM-dithiothreitol, indicating that the type IV molecule is stabilized within the basement membrane by covalent cross-links. However, various forms of type IV collagen molecule were extractable by means of increasingly severe proteolytic conditions. Type IV collagen tetramers (‘spiders’) lacking only the C-terminal globular region (NC1) were further digested to the ‘long-form’ 7S fragment and an assortment of helical rod-like molecules derived from the ‘leg’ region. These molecules were separated by salt fractionation and examined by rotary-shadowing electron microscopy. Isolation of these fractions from placenta which had been reduced with NaB3H4 revealed that both the 7S (N-terminal) and C-terminal regions contained significant proportions of reducible lysine-derived cross-links. These cross-links were shown to be exclusively the stable oxo-imine hydroxylysino-5-oxonorleucine. The number of the cross-links per molecule was significantly lower than might be expected in order to fully stabilize the molecule. These results suggest that the keto-imine cross-links in type IV collagen have been stabilized in part by conversion into an unknown non-reducible form, although a sensitive immunoassay failed to show the presence of any pyridinoline. Comparison with the fibrous collagen from placenta suggested that the rate of this conversion is much greater in basement-membrane collagen.

scholarly journals Shift in collagen type as an early response to induction of the metanephric mesenchyme.

1981 ◽  
Vol 89 (2) ◽  
pp. 276-283 ◽  
Author(s):  
P Ekblom ◽  
E Lehtonen ◽  
L Saxén ◽  
R Timpl
Keyword(s):  
Basal Lamina ◽  
Type Iv Collagen ◽  
Early Response ◽  
Type I ◽  
Metanephric Mesenchyme ◽  
Type Iv ◽  
Interstitial Collagens ◽  
Membrane Components

Conversion of the nephrogenic mesenchyme into epithelial tubules requires an inductive stimulus from the ureter bud. Here we show with immunofluorescence techniques that the undifferentiated mesenchyme before induction expresses uniformly type I and type III collagens. Induction both in vivo and in vitro leads to a loss of these proteins and to the appearance of basement membrane components including type IV collagen. This change correlates both spatially and temporally with the determination of the mesenchyme and precedes and morphological events. During morphogenesis, type IV collagen concentrates at the borders of the developing tubular structures where, by electron microscopy, a thin, often discontinuous basal lamina was seen to cover the first pretubular cell aggregates. Subsequently, the differentiating tubules were surrounded by a well-developed basal lamina. No loss of the interstitial collagens was seen in the metanephric mesenchyme when brought into contact with noninducing tissues or when cultured alone. Similar observations were made with nonnephrogenic mesenchyme (salivary, lung) when exposed to various heterotypic tissues known to induce tubules in the nephrogenic mesenchyme. The sequential shift in the composition of the extracellular matrix from an interstitial, mesenchymal type to a differentiated, epithelial type is so far the first detectable response of the nephrogenic mesenchyme to the tubule-inducing signal.

In vitro and post-transplantation differentiation of human keratinocytes grown on the human type IV collagen film of a bilayered dermal substitute

1991 ◽  
Vol 193 (2) ◽  
pp. 310-319 ◽  
Author(s):  
Estelle Tinois ◽  
Jerome Tiollier ◽  
Martine Gaucherand ◽  
Henri Dumas ◽  
Michel Tardy ◽  
...  
Keyword(s):  
Type Iv Collagen ◽  
Human Keratinocytes ◽  
Dermal Substitute ◽  
Post Transplantation ◽  
Collagen Film ◽  
Human Type ◽  
Type Iv

scholarly journals Mapping the Contact Sites of the Escherichia coli Division-Initiating Proteins FtsZ and ZapA by BAMG Cross-Linking and Site-Directed Mutagenesis

2018 ◽  
Vol 19 (10) ◽  
pp. 2928 ◽  
Author(s):  
Winfried Roseboom ◽  
Madhvi Nazir ◽  
Nils Meiresonne ◽  
Tamimount Mohammadi ◽  
Jolanda Verheul ◽  
...  
Keyword(s):  
Site Directed Mutagenesis ◽  
Cross Linking ◽  
Directed Mutagenesis ◽  
Amino Acid Residues ◽  
Binding Interface ◽  
Tetrameric Structure ◽  
Z Ring ◽  
Cross Links ◽  
Chemical Cross Linking

Cell division in bacteria is initiated by the polymerization of FtsZ at midcell in a ring-like structure called the Z-ring. ZapA and other proteins assist Z-ring formation and ZapA binds ZapB, which senses the presence of the nucleoids. The FtsZ–ZapA binding interface was analyzed by chemical cross-linking mass spectrometry (CXMS) under in vitro FtsZ-polymerizing conditions in the presence of GTP. Amino acids residue K42 from ZapA was cross-linked to amino acid residues K51 and K66 from FtsZ, close to the interphase between FtsZ molecules in protofilaments. Five different cross-links confirmed the tetrameric structure of ZapA. A number of FtsZ cross-links suggests that its C-terminal domain of 55 residues, thought to be largely disordered, has a limited freedom to move in space. Site-directed mutagenesis of ZapA reveals an interaction site in the globular head of the protein close to K42. Using the information on the cross-links and the mutants that lost the ability to interact with FtsZ, a model of the FtsZ protofilament–ZapA tetramer complex was obtained by information-driven docking with the HADDOCK2.2 webserver.

scholarly journals Multiple mechanisms of dissociated epidermal cell spreading.

1983 ◽  
Vol 96 (1) ◽  
pp. 63-67 ◽  
Author(s):  
K S Stenn ◽  
J A Madri ◽  
T Tinghitella ◽  
V P Terranova
Keyword(s):  
Serum Albumin ◽  
Epidermal Cell ◽  
Type Iv Collagen ◽  
Cell Spreading ◽  
Specific Protein ◽  
Epidermal Cells ◽  
Type Iv ◽  
Basement Membrane Protein ◽  
Specific Proteins

To test the possibility that epidermal cells use a common basement membrane protein whenever they spread, in vitro experiments were conducted using trypsin-dissociated guinea pig epidermal cells and the following proteins: human serum, bovine serum albumin, serum fibronectin, Type IV collagen, laminin, and epibolin (a recently described serum glycoprotein which supports epidermal cell spreading; Stenn, K.S., 1981, Proc. Natl. Acad. Sci. U.S.A. 78:6907.). When the cells were added to media containing the specific proteins, all the tested proteins, except for serum albumin, supported cell spreading. Added to protein-coated substrates in defined media, the cells spread on fibronectin, epibolin, and laminin-Type IV collagen, but not on albumin or whole serum. In none of these experiments were the results qualitatively affected by the presence of cycloheximide. Antibodies to a specific protein blocked cell spreading on that protein but not on the other active proteins, e.g. whereas antibodies to epibolin blocked cell spreading on epibolin, they did not affect spreading on fibronectin, collagen, or laminin. In a second assay in which the cells were allowed to adhere to tissue culture plastic before the protein-containing medium was added, the cells spread only if the medium contained epibolin. Moreover, under these conditions the spreading activity of whole serum and plasma was neutralized by antiepibolin antibodies. These results support the conclusion that dissociated epidermal cells possess multiple spreading modes which depend, in part, on the proteins of the substrate, proteins of the medium, and the sequence of cell adhesion and protein exposure.

THERMOREVERSIBLE CROSS-LINKING MALEIC ANHYDRIDE GRAFTED CHLOROBUTYL RUBBER WITH HYDROGEN BONDS (COMBINED WITH IONIC INTERACTIONS)

2014 ◽  
Vol 87 (3) ◽  
pp. 459-470 ◽  
Author(s):  
Lin Li ◽  
Jin Kuk Kim
Keyword(s):  
Hydrogen Bonds ◽  
Maleic Anhydride ◽  
Ionic Interactions ◽  
Cross Linking ◽  
External Energy ◽  
Scanning Calorimetry ◽  
Ionic Bonds ◽  
Cross Links ◽  
Ionic Hydrogen Bonds ◽  
Chlorobutyl Rubber

ABSTRACT Thermoreversible cross-linking polymers are designed based on reversible cross-linking bonds. These bonds are able to reversibly dissociate and associate upon the input of external energy, such as heat or light. Reprocessibility is possible for this kind of material. The objective was to thermoreversibly cross-link maleic anhydride grafted chlorobutyl rubber (MAH-g-CIIR) via a reaction with octadecylamine, with an excess to obtain amide-salts, which form both hydrogen bonds and ionic interactions. X-ray diffraction experiments showed the presence of microphase-separated aggregates that acted as physical cross-links for both the MAH-g-CIIR precursor and amide-salts. The tensile properties were improved by converting MAH-g-CIIR to amide-salts, because of the combination of hydrogen bonding and ionic interactions. The cross-linked materials could be repeatedly compression molded at 155 °C into homogeneous films. The differential scanning calorimetry curves and Fourier transform infrared spectra indicate that hydrogen bonds are of a thermoreversible nature, but the recovery of ionic bonds is impossible. After treatment with heating-cooling for up to three cycles, the tensile strength of the thermoreversible cross-linking CIIR was greatly reduced. The gradual reduction in the effectiveness of the ionic-hydrogen bonds is the major contribution to the reprocessibility of these materials.

scholarly journals The pathogenesis of Alport syndrome involves type IV collagen molecules containing the α3(IV) chain: Evidence from anti-GBM nephritis after renal transplantation

1992 ◽  
Vol 42 (1) ◽  
pp. 179-187 ◽  
Author(s):  
Billy G. Hudson ◽  
Raghuram Kalluri ◽  
Sripad Gunwar ◽  
Manfred Weber ◽  
Fernando Ballester ◽  
...  
Keyword(s):  
Renal Transplantation ◽  
Alport Syndrome ◽  
Type Iv Collagen ◽  
Type Iv ◽  
Collagen Molecules
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