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1.
Int J Biol Macromol ; 164: 748-758, 2020 Dec 01.
Article in English | MEDLINE | ID: mdl-32693139

ABSTRACT

Artificial sweeteners (AS) are widely used as sugar substitutes because natural sweetener (sugar) leads to a number of health issues, including diabetes, obesity, and tooth decay. Since natural sugar (sucrose), diabetes and skin are highly interlinked, and also sucrose is known to inhibit the fibrillation of collagen, the major protein of the skin, a study on the impact of AS on collagen is important and essential. Herein, we have studied the influence of commonly used AS such as Sucralose (SUC), Aspartame (APM), and Saccharin (SAC) on the structure, stability, and fibrillation of collagen using various spectroscopic methods. The circular dichroism and turbidity results suggest that the AS does not disrupt the triple helix structure and also the fibrillar property of collagen, respectively. The fibrillar morphology was sustained, although there was a trivial difference in the entanglement of fibrils in the presence of SAC, compared to native collagen fibrils. The thermal stability of collagen is maintained in the presence of AS. Fluorescence and STD-NMR results indicate that the interaction between AS and collagen was weak, which supports the intact structure, stability, and fibrillation property of collagen. The current study thus suggests that the chosen AS does not influence collagen properties.


Subject(s)
Collagen Type I/ultrastructure , Fibril-Associated Collagens/ultrastructure , Sucrose/adverse effects , Sweetening Agents/pharmacology , Aspartame/adverse effects , Aspartame/pharmacology , Collagen Type I/chemistry , Collagen Type I/drug effects , Diabetes Mellitus/epidemiology , Fibril-Associated Collagens/chemistry , Fibril-Associated Collagens/drug effects , Humans , Obesity/epidemiology , Saccharin/adverse effects , Saccharin/pharmacology , Sucrose/analogs & derivatives , Sucrose/pharmacology , Sweetening Agents/adverse effects
2.
Mar Drugs ; 17(8)2019 Aug 07.
Article in English | MEDLINE | ID: mdl-31394862

ABSTRACT

Acid-soluble collagen (ASC) and pepsin-soluble collagen (PSC) from the skin of river puffer (ASC-RP and PSC-RP) and tiger puffer (ASC-TP and PSC-TP) were extracted and physicochemically examined. Denaturation temperature (Td) for all the collagens was found to be 25.5-29.5 °C, which was lower than that of calf skin collagen (35.9 °C). Electrophoretic patterns indicated all four samples were type I collagen with molecular form of (α1)2α2. FTIR spectra confirmed the extracted collagens had a triple-helical structure, and that the degree of hydrogen bonding in ASC was higher than PSC. All the extracted collagens could aggregate into fibrils with D-periodicity. The fibril formation rate of ASC-RP and PSC-RP was slightly higher than ASC-TP and PSC-TP. Turbidity analysis revealed an increase in fibril formation rate when adding a low concentration of NaCl (less than 300 mM). The fibril formation ability was suppressed with further increasing of NaCl concentration, as illustrated by a reduction in the turbidity and formation degree. SEM analysis confirmed the well-formed interwoven structure of collagen fibrils after 24 h of incubation. Summarizing the experimental results suggested that the extracted collagens from the skin of river puffer and tiger puffer could be considered a viable substitute to mammalian-derived collagens for further use in biomaterial applications.


Subject(s)
Collagen Type I/chemistry , Fibril-Associated Collagens/chemistry , Fish Proteins/chemistry , Skin/chemistry , Takifugu/metabolism , Tetraodontiformes/metabolism , Acids/chemistry , Amino Acids/chemistry , Animals , Hydrogen Bonding , Pepsin A/chemistry , Rivers , Solubility , Temperature
3.
Biomater Sci ; 4(4): 711-23, 2016 Apr.
Article in English | MEDLINE | ID: mdl-26902645

ABSTRACT

Collagen is used extensively for tissue engineering due to its prevalence in connective tissues and its role in defining tissue biophysical and biological signalling properties. However, traditional collagen-based materials fashioned from atelocollagen and telocollagen have lacked collagen densities, multi-scale organization, mechanical integrity, and proteolytic resistance found within tissues in vivo. Here, highly interconnected low-density matrices of D-banded fibrils were created from collagen oligomers, which exhibit fibrillar as well as suprafibrillar assembly. Confined compression then was applied to controllably reduce the interstitial fluid while maintaining fibril integrity. More specifically, low-density (3.5 mg mL(-1)) oligomer matrices were densified to create collagen-fibril constructs with average concentrations of 12.25 mg mL(-1) and 24.5 mg mL(-1). Control and densified constructs exhibited nearly linear increases in ultimate stress, Young's modulus, and compressive modulus over the ranges of 65 to 213 kPa, 400 to 1.26 MPa, and 20 to 150 kPa, respectively. Densification also increased construct resistance to collagenase degradability. Finally, this process was amenable to creating high-density cellularized tissues; all constructs maintained high cell viability (at least 97%) immediately following compression as well as after 1 day and 7 days of culture. This method, which integrates the suprafibrillar assembly capacity of oligomers and controlled fluid reduction by confined compression, supports the rational and scalable design of a broad range of collagen-fibril materials and cell-encapsulated tissue constructs for tissue engineering applications.


Subject(s)
Collagen/chemistry , Extracellular Matrix/chemistry , Fibril-Associated Collagens/chemistry , Tissue Engineering , Biomechanical Phenomena , Collagen/physiology , Extracellular Matrix/physiology , Fibril-Associated Collagens/physiology , Materials Testing/methods , Models, Biological , Pressure , Stress, Mechanical
4.
Biomaterials ; 35(21): 5472-81, 2014 Jul.
Article in English | MEDLINE | ID: mdl-24731707

ABSTRACT

While most fracture-mechanics investigations on bone have been performed at low strain rates, physiological fractures invariably occur at higher loading rates. Here, at strain rates from 10(-5) to 10(-1) s(-1), we investigate deformation and fracture in bone at small length-scales using in situ small-angle x-ray scattering (SAXS) to study deformation in the mineralized collagen fibrils and at the microstructural level via fracture-mechanics experiments to study toughening mechanisms generating toughness through crack-tip shielding. Our results show diminished bone toughness at increasing strain rates as cracks penetrate through the osteons at higher strain rates instead of deflecting at the cement lines, which is a prime toughening mechanism in bone at low strain rates. The absence of crack deflection mechanisms at higher strain rates is consistent with lower intrinsic bone matrix toughness. In the SAXS experiments, higher fibrillar strains at higher strain rates suggest less inelastic deformation and thus support a lower intrinsic toughness. The increased incidence of fracture induced by high strain rates can be associated with a loss in toughness in the matrix caused by a strain rate induced stiffening of the fibril ductility, i.e., a "locking-up" of the viscous sliding and sacrificial bonding mechanisms, which are the origin of inelastic deformation (and toughness) in bone at small length-scales.


Subject(s)
Bone Matrix/diagnostic imaging , Fractures, Bone/diagnostic imaging , X-Ray Diffraction/methods , Biomechanical Phenomena , Bone Matrix/physiology , Fibril-Associated Collagens/chemistry , Humans , Male , Microscopy, Electron, Scanning , Middle Aged , Radiography , Scattering, Small Angle
5.
Biochem J ; 459(1): 217-27, 2014 Apr 01.
Article in English | MEDLINE | ID: mdl-24428702

ABSTRACT

Collagen XXII, a FACIT (fibril-associated collagen with interrupted triple helices), is expressed at the myotendinous junction and the articular surface of joint cartilage. Cellular receptors like collagen-binding integrins are known to bind collagens with distinct binding motifs following the sequence GXOGER. In the present study, we demonstrate the sequences GLQGER and GFKGER as novel binding motifs between collagen XXII and collagen-binding integrins, especially α2ß1 integrin. Solid-phase assays and surface plasmon resonance spectroscopy revealed a direct interaction between α2ß1 integrin and the motif GFKGER. In addition, immunohistochemical analysis demonstrated partial co-localization of collagen XXII, α2ß1 integrin and α11ß1 integrin at the myotendinous junction. Furthermore, computational modelling of the motifs GLQGER and GFKGER showed perfect fitting of the sequences into the binding pocket of collagen-binding integrins. Taken together, we demonstrated that collagen XXII interacts with collagen-binding integrins via the new motifs GLQGER and GFKGER.


Subject(s)
Fibril-Associated Collagens/metabolism , Integrins/metabolism , Amino Acid Motifs/physiology , Animals , CHO Cells , Cell Line, Tumor , Cricetulus , Fibril-Associated Collagens/chemistry , Fibril-Associated Collagens/genetics , Humans , Integrins/chemistry , Integrins/genetics , Mice, Inbred C57BL , Protein Binding/physiology , Protein Structure, Secondary , Protein Structure, Tertiary
6.
Zh Evol Biokhim Fiziol ; 50(4): 245-54, 2014.
Article in Russian | MEDLINE | ID: mdl-25775860

ABSTRACT

Fibril-associated collagens with interrupted triple helices (FACITs) form one of the subfamilies of collagen family. Being minor components of connective tissues in multicellular animals, FACITs play an important role in structurization of extracellular matrix whose peculiarities determine differences among tissues. FACITs take part in regulation of the sizes of banded collagen fibrils and are also a link between diverse components of extracellular matrix and cells in different tissues. The functional characteristics of FACIT molecules are determined by peculiarities of α-chain structure (interruptions in collagenous domains and module structure of N-terminal noncollagenous regions), trimeric molecules (trimerization domains), and supramolecular assemblies (mainly, association with banded fibrils and inability to form homopolymeric suprastructural aggregates). The evolution of FACITs is also discussed. A hypothetical model of structural changes leading to formation of FACIT subfamily is propounded.


Subject(s)
Evolution, Molecular , Fibril-Associated Collagens/chemistry , Animals , Fibril-Associated Collagens/genetics , Fibril-Associated Collagens/metabolism , Humans , Protein Structure, Tertiary
7.
Phys Rev E Stat Nonlin Soft Matter Phys ; 83(4 Pt 2): 046126, 2011 Apr.
Article in English | MEDLINE | ID: mdl-21599259

ABSTRACT

Traditional fiber bundles models (FBMs) have been an effective tool to understand brittle heterogeneous systems. However, fiber bundles in modern nano- and bioapplications demand a new generation of FBM capturing more complex deformation processes in addition to damage. In the context of loose bundle systems and with reference to time-independent plasticity and soft biomaterials, we formulate a generalized statistical model for ductile fracture and nonlinear elastic problems capable of handling more simultaneous deformation mechanisms by means of two order parameters (as opposed to one). As the first rational FBM for coupled damage problems, it may be the cornerstone for advanced statistical models of heterogeneous systems in nanoscience and materials design, especially to explore hierarchical and bio-inspired concepts in the arena of nanobiotechnology. Applicative examples are provided for illustrative purposes at last, discussing issues in inverse analysis (i.e., nonlinear elastic polymer fiber and ductile Cu submicron bars arrays) and direct design (i.e., strength prediction).


Subject(s)
Biocompatible Materials/chemistry , Nanostructures/chemistry , Anisotropy , Biotechnology/methods , Collagen/chemistry , Copper/chemistry , Electrochemistry/methods , Fibril-Associated Collagens/chemistry , Materials Testing , Models, Statistical , Nanotechnology/methods , Polymers/chemistry , Tensile Strength , Time Factors , Tissue Engineering/methods
8.
Eur Cell Mater ; 12: 57-63, 2006 Nov 02.
Article in English | MEDLINE | ID: mdl-17083085

ABSTRACT

Adult articular cartilage by dry weight is two-thirds collagen. The collagen has a unique molecular phenotype. The nascent type II collagen fibril is a heteropolymer, with collagen IX molecules covalently linked to the surface and collagen XI forming the filamentous template of the fibril as a whole. The functions of collagens IX and XI in the heteropolymer are far from clear but, evidently, they are critically important since mutations in COLIX and COLXI genes can result in chondrodysplasia syndromes. Here we review what is known of the collagen assembly and present new evidence that collagen type III becomes covalently added to the polymeric fabric of adult human articular cartilage, perhaps as part of a matrix repair or remodelling process.


Subject(s)
Cartilage, Articular/chemistry , Fibril-Associated Collagens/metabolism , Amino Acid Sequence , Animals , Cartilage, Articular/cytology , Fibril-Associated Collagens/analysis , Fibril-Associated Collagens/chemistry , Fibril-Associated Collagens/ultrastructure , Humans , Molecular Sequence Data , Peptides/analysis , Peptides/chemistry , Peptides/isolation & purification , Protein Isoforms/analysis , Protein Isoforms/chemistry , Protein Isoforms/metabolism , Protein Isoforms/ultrastructure , Protein Processing, Post-Translational
9.
J Biol Chem ; 281(2): 1048-57, 2006 Jan 13.
Article in English | MEDLINE | ID: mdl-16269408

ABSTRACT

Endostatin is an endogenous inhibitor of tumor angiogenesis and tumor growth. It has two pairs of disulfide bonds in a unique nested pattern, which play a key role in its native conformation, stability, and activity. Here, we constructed a disulfide-deficient variant of endostatin, endo-all-Ala, to examine the effects of the two disulfide bonds on fibrillogenesis of endostatin under nondenaturing conditions. Based on thioflavin T fluorescence, atomic force microscopy, far-UV circular dichroism, and Fourier transform infrared spectroscopy, we found that endo-all-Ala, which has a higher alpha-helical content compared with wild type, is prone to forming fibrils in a pH-dependent manner. Subsequently, more hydrophobic patches with a lower stability of endo-all-Ala were observed when compared with wild type, which possibly contributes to the propensity of amyloid formation of endo-all-Ala. To our surprise, the significant increase of the alpha-helical content in endostatin induced by trifluoroethanol can also facilitate fibril formation. In addition, the cytotoxicity of fibrillar aggregates of endo-all-Ala, which were generated at different stages of the fibril formation process, was evaluated by cell viability assay. The results indicate that the cytotoxicity is not due to the fibrils but rather due to the granular aggregates of endo-all-Ala. Moreover, endostatin was interestingly found to be reduced by glutathione at physiological concentrations. Our present work not only elucidates the correlation between the existence of disulfide bonds and the fibril formation of endostatin but also may provide some insights into the structural and functional basis of endostatin in Alzheimer disease brains.


Subject(s)
Endostatins/chemistry , Fibril-Associated Collagens/chemistry , Alanine/chemistry , Alzheimer Disease/metabolism , Animals , Benzothiazoles , Cell Survival , Circular Dichroism , Disulfides/chemistry , Escherichia coli/metabolism , Fluorescent Dyes/pharmacology , Glutathione/metabolism , Hydrogen-Ion Concentration , Light , Microscopy, Atomic Force , Neovascularization, Pathologic , PC12 Cells , Protein Conformation , Protein Structure, Tertiary , Rats , Scattering, Radiation , Spectroscopy, Fourier Transform Infrared , Temperature , Tetrazolium Salts/pharmacology , Thiazoles/chemistry , Thiazoles/pharmacology , Time Factors , Tryptophan/chemistry , Ultraviolet Rays
10.
FEBS Lett ; 552(2-3): 91-4, 2003 Sep 25.
Article in English | MEDLINE | ID: mdl-14527666

ABSTRACT

We suggest that there is an evolutionary relationship between von Willebrand factor A-domain-related protein (WARP), and the fibril-associated collagen with interrupted triple helix (FACIT) and FACIT-like subfamilies of collagens. Data from a comparison of amino acid sequences, domain organisation and chromosomal location are consistent with the hypothesis that WARP and these collagens share a common collagen ancestor. In support of this is the observation that the WARP 3' coding region is GC-rich suggesting that this may represent the remnant of a triple helix protein domain which WARP has 'lost' during evolution.


Subject(s)
Extracellular Matrix Proteins/chemistry , Extracellular Matrix Proteins/genetics , Fibril-Associated Collagens/chemistry , Fibril-Associated Collagens/genetics , Animals , Chromosome Mapping , Evolution, Molecular , Humans , Mice , Models, Genetic , Multigene Family , Protein Structure, Tertiary , Sequence Homology, Amino Acid
11.
Matrix Biol ; 21(4): 369-77, 2002 Jun.
Article in English | MEDLINE | ID: mdl-12128074

ABSTRACT

The present study examined the hypothesis that collagen fibril diameter and crimp angle in ruptured human Achilles tendons differed from that of intact ones. Tissue samples were obtained from the central core (distal core) and the posterior periphery (distal superficial) at the rupture site, and the proximally intact (proximal superficial) part of the tendon in 10 subjects (38+/-8 years) with a complete tendon rupture. For comparisons corresponding tissue samples were procured from age (38+/-7 years) and gender matched intact Achilles tendons during routine forensic autopsy. The cross-sectional area density and diameter distribution of fibrils were analyzed using stereological techniques of digitized electron microscopy biopsy cross-sections, while crimp angle was measured by the changing banding pattern of collagen fibers when rotated between crossed polars. Nine of 10 persons with tendon ruptures reported that the injury did not occur during exceedingly large forces, and none experienced any symptoms in the days or months prior to the injury. Fibril diameter distribution showed no region-specific differences in either the ruptured or intact tendons for either group. However, in the distal core there were fewer fibrils in the ruptured compared to the intact tendons in 60-150 nm range, P<0.01. Similarly, in the distal superficial portion there were fewer fibrils in the ruptured compared to the intact tendons in the 90-120 nm range, 2P<0.05, while there were no differences in the proximal superficial tendons. Crimp angle did not display any region-specific differences, or any difference between the rupture and intact tendons. In conclusion, these data suggest that although crimp morphology is unchanged there appears to be a site-specific loss of larger fibrils in the core and periphery of the Achilles tendon rupture site. Moreover, the lack of symptoms prior to the rupture suggests that clinical tendinopathy is not an etiological factor in complete tendon ruptures.


Subject(s)
Achilles Tendon/chemistry , Achilles Tendon/pathology , Fibril-Associated Collagens/analysis , Fibril-Associated Collagens/chemistry , Rupture/pathology , Tendon Injuries/pathology , Achilles Tendon/cytology , Adult , Female , Humans , Male , Microscopy, Electron , Microscopy, Polarization , Middle Aged , Rupture/metabolism , Tendon Injuries/metabolism , Tensile Strength
12.
Matrix Biol ; 21(1): 63-6, 2002 Jan.
Article in English | MEDLINE | ID: mdl-11827793

ABSTRACT

The FACIT collagens bind to the surface of collagen fibrils linking them with other matrix molecules. Bioinformatics analysis of cDNA clone DKFZp564B052 showed that it resembled the FACIT collagens and was therefore designated collagen alpha 1(XXI). Phylogenetic analyses of the N-terminal NC3 domains of alpha 1(XXI) and other FACIT collagens showed that (i) alpha 1(XXI) clustered with the FACIT collagens; (ii) collagen alpha 1(XXI) arose before the divergence of alpha 1(XII), alpha 1(XIV) and alpha 1(XX); (iii) collagen alpha 1(XIV) derived from the C-terminal region of the NC3 domain of a collagen alpha 1(XII)-like molecule; and (iv) collagen alpha 1(XX) derived from a collagen alpha 1(XIV)-like molecule. This study provides a framework for the evolution of the FACIT collagens which will be of value in linking NC3 domains with their functions.


Subject(s)
Computational Biology/methods , Evolution, Molecular , Fibril-Associated Collagens/analysis , Animals , Computational Biology/trends , Databases, Genetic , Fibril-Associated Collagens/chemistry , Fibril-Associated Collagens/genetics , Humans , Phylogeny , Protein Structure, Tertiary
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