Embryonic avian cornea contains layers of collagen with greater than average stability.

A unique morphological feature of the embryonic avian cornea is the uniformity of its complement of striated collagen fibrils, each of which has a diameter of 25 nm. We have asked whether this apparent morphological uniformity also reflects an inherent uniformity of the structural and physical properties of these fibrils. For this we have examined the in situ thermal stability of the type I collagen within these fibrils. Corneal tissue sections were reacted at progressively higher temperatures with conformation-dependent monoclonal antibodies directed against the triple-helical domain of the type I collagen molecule. These studies show that the cornea contains layers of collagen fibrils with greater than average stability. The two most prominent of these extend uninterrupted across the entire width of the cornea, and then appear to insert into thick bundles of scleral collagen, which in turn appear to insert into the scleral ossicles, a ring of bony plates which circumscribe the sclera of the avian eye. Once formed, the bands may act to stabilize the shape of the cornea or, conversely, to alter it during accommodation.

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Molecular mobility in the gap regions of type 1 collagen fibrils

Bioscience Reports ◽

10.1007/bf01115010 ◽

1986 ◽

Vol 6 (2) ◽

pp. 221-226 ◽

Cited By ~ 13

Author(s):

R. D. B. Fraser ◽

B. L. Trus

Keyword(s):

Type I Collagen ◽

Collagen Fibrils ◽

Collagen Molecule ◽

Type I ◽

Amino Acid Residues ◽

Linear Distribution ◽

Uniform Distributions ◽

Imino Acid ◽

Hydropathy Index

Recent studies of the structure of Type I collagen fibrils (Piez and Trus, Biosci. Rep.1:801–810, 1981; Fraser, MacRae, Miller and Suzuki, J. Mol. Biol.167:497–521, 1983) suggest that the segments of the collagen molecule which comprise the gap region are more mobile than those which comprise the overlap region. We have analyzed the distribution of amino acid residues and triplet types between the two regions, and find significantly non-uniform distributions for Ala, Gln, His, Hyp, Leu, Phe, and Tyr, and for triplets containing two imino acid residues. Taken together with the lower packing density in the gap region these observations provide a basis for understanding the greater mobility of the molecular segments in the gap region. In addition, we have examined the linear distribution of residue types in the two regions and also the hydropathy profile (Kyte and Doolittle, J. Mol. Biol.157: 105–113, 1982). These reveal a segment of the gap region comprising helical residues 165–173, 399–407, 633–641 and 867–975 which has the highest hydropathy index, is devoid of charged residues, and contains very high proportions of Ala, Hyp and Phe.

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Thermal stability of the helical structure of type IV collagen within basement membranes in situ: determination with a conformation-dependent monoclonal antibody.

The Journal of Cell Biology ◽

10.1083/jcb.99.4.1405 ◽

1984 ◽

Vol 99 (4) ◽

pp. 1405-1409 ◽

Cited By ~ 9

Author(s):

T F Linsenmayer ◽

E Gibney ◽

J M Fitch ◽

J Gross ◽

R Mayne

Keyword(s):

Thermal Stability ◽

Type Iv Collagen ◽

Helical Structure ◽

Basement Membranes ◽

Enzyme Linked Immunosorbent Assay ◽

Tissue Sections ◽

Type Iv ◽

The Stability ◽

Thermal Stability Of

To examine the thermal stability of the helical structure of type IV collagen within basement membranes in situ, we have employed indirect immunofluorescence histochemistry performed at progressively higher temperatures using a conformation-dependent antibody, IV-IA8. We previously observed by competition enzyme-linked immunosorbent assay that, in neutral solution, the helical epitope to which this antibody binds undergoes thermal denaturation over the range of 37-40 degrees C. In the present study, we have reacted unfixed cryostat tissue sections with this antibody at successively higher temperatures. We have operationally defined denaturation as the point at which type IV-specific fluorescence is no longer detectable. Under these conditions, the in situ denaturation temperature of this epitope in most basement membranes is 50-55 degrees C. In capillaries and some other small blood vessels the fluorescent signal is still clearly detectable at 60 degrees C, the highest temperature at which we can confidently use this technique. We conclude that the stability of the helical structure of type IV collagen within a basement membrane is considerably greater than it is in solution, and that conformation-dependent monoclonal antibodies can be useful probes for investigations of molecular structure in situ.

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Thermal stability of human-fibroblast-collagenase-cleavage products of type-I and type-III collagens

Biochemical Journal ◽

10.1042/bj2470725 ◽

1987 ◽

Vol 247 (3) ◽

pp. 725-729 ◽

Cited By ~ 26

Author(s):

C C Danielsen

Keyword(s):

Thermal Stability ◽

Human Fibroblast ◽

Type I Collagen ◽

Type Iii Collagen ◽

Type I ◽

Type Iii ◽

Melting Temperatures ◽

Large Type ◽

Fibroblast Collagenase ◽

Thermal Stability Of

Rat skin type-I and type-III collagens were degraded by human fibroblast collagenase at a temperature below the ‘melting’ temperature for the two resulting fragments, namely the N-terminal three-fourths, TCA, and the C-terminal one-fourth, TCB. The specific cleavage of the collagen was confirmed by electrophoresis and determination of molecular length by electron microscopy. The two fragments were separated by gel filtration and the thermal stabilities of the isolated fragments were determined. For type-I collagen, the ‘melting’ temperatures of the two fragments were found to differ by only 0.5 degrees C and were 4.5-5.0 degrees C below that of the uncleaved molecule. The ‘melting’ temperatures of the uncleaved molecule and the N-terminal fragment were independent of the extent of N-terminal intramolecular cross-linking. For type-III collagen, the ‘melting’ temperatures of the fragments were found to differ by 1.3 degrees C. The small fragments of the two types of collagen ‘melted’ at the same temperature, whereas the large type-III fragment ‘melted’ at a slightly higher temperature than did the large type-I fragment. Reduction of the disulphide bonds located in the C-terminal type-III fragment did not affect the thermal stability of this fragment. The thermal stability of uncleaved type-III collagen was found to be variable, but the reason for this is not known at present.

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Normal Thermal Stability of an Overmodified Type I Collagen Despite a Structural Mutation within the Triple Helical Region in a Case of Osteogenesis Irnperfecta Type IVB

Annals of the New York Academy of Sciences ◽

10.1111/j.1749-6632.1988.tb55318.x ◽

1988 ◽

Vol 543 (1 Third Interna) ◽

pp. 83-84 ◽

Cited By ~ 1

Author(s):

P. M. ROYCE ◽

A. SUPERTI-FURGA ◽

V. H. RAO ◽

B. STEINMANN

Keyword(s):

Thermal Stability ◽

Type I Collagen ◽

Type I ◽

Structural Mutation ◽

Thermal Stability Of ◽

Helical Region

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Organization and characterization of fibrillar collagens in fish scales in situ and in vitro

Journal of Cell Science ◽

10.1242/jcs.103.1.273 ◽

1992 ◽

Vol 103 (1) ◽

pp. 273-285 ◽

Cited By ~ 1

Author(s):

L. ZYLBERBERG ◽

J. BONAVENTURE ◽

L. COHEN-SOLAL ◽

D. J. HARTMANN ◽

J. BEREITERHAHN

Keyword(s):

Cyanogen Bromide ◽

Type I Collagen ◽

Collagen Fibrils ◽

Type I ◽

Fish Scales ◽

Fibrillar Collagens ◽

Collagen Genes

The characterization of the fibrillar collagens and the cellular control of their spatial deposition were studied in fish scales using immunofluorescence, electron microscopy, electrophoretic and HPLC analyses, immunoprecipitation and hybridization with cDNA probes. This study was carried out on undisturbed and regenerating scales in situ and in organ and cell cultures from regenerating scales. The hyposquamal scleroblasts forming a pseudoepithelium show an apico-basal polarization and synthesize thick collagen fibrils (100 nm) organized in a plywood pattern as long as the integrity of the cell-cell and cell-collagenous matrix contacts are preserved. In culture, scleroblasts become fibroblastlike and produce an unordered meshwork of thin collagen fibrils (30 nm). Comparison of the synthesized collagens in culture with those extracted from the scales indicates that culture conditions modify fibrillogenesis but do not change the expression of fibrillar collagen genes. Type I collagen, the predominent component, is associated with the minor type V collagen. Type III collagen was not present. In type I collagen, a third chain, α3 chain, was identified. The ratio between the 3 chains suggests the coexistence of two heterotrimers (α(I))2 α2(I) and αl(I) α2(I) α3(I). Analysis by HPLC and electrophoresis of the cyanogen bromide-derived peptides obtained from the purified a3 chain support the hypothesis that α(I) and α3(I) chains are encoded by two different genes. The presence of the two types of heterotrimers in vivo as well as in vitro could correspond to an innate property of the goldfish scleroblasts. Despite the fact that teleost cyanogen bromide-derived peptides differ from those of higher vertebrates, homologies with the mammalian collagen genes (human, for example) are sufficient to allow the detection of mRNA transcripts for αl(I), α2(I) and α2(V) from confluent scleroblast cultures with human probes.

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Thermal Properties of Mineralized and Non Mineralized Type I Collagen in Bone

MRS Proceedings ◽

10.1557/proc-724-n7.6 ◽

2002 ◽

Vol 724 ◽

Cited By ~ 3

Author(s):

L. F. Lozano ◽

M. A. Peña-Rico ◽

H. Jang-Cho ◽

A. Heredia ◽

E. Villarreal ◽

...

Keyword(s):

Thermal Stability ◽

Type I Collagen ◽

Combustion Process ◽

Stability Loss ◽

Human Bone ◽

Type I ◽

Global Effect ◽

Cross Links ◽

The Stability ◽

Thermal Stability Of

AbstractThe research about the structural stability of bone, as a composite material, compromises a complete understanding of the interaction between the mineral and organic phases. The thermal stability of human bone and type I collagen extracted from human bone by different methods was studied in order to understand the interactions between the mineral and organic phases when is affected by a degradation/combustion process. The experimental techniques employed were calorimetry and infrared spectroscopy (FTIR) techniques. The extracted type I collagens result to have a bigger thermal stability with a Tmax at 500 and 530 Celsius degrees compared with the collagen present in bone with Tmax at 350 Celsius degrees. The enthalpy value for the complete degradation/combustion process were similar for all the samples, being 8.4 +- 0.11 kJ/g for recent bones diminishing with the antiquity, while for extracted collagens were 8.9 +- 0.07 and 7.9 +-1.01 kJ/g. These findings demonstrate that the stability loss of type I collagen is due to its interactions with the mineral phase, namely carbonate hydroxyapatite. This cause a change in the molecular properties of the collagen during mineralization, specifically in its cross-links and other chemical interactions, which have a global effect over the fibers elasticity, but gaining tensile strength in bone as a whole tissue. We are applying this characterization to analyze the diagenetic process of bones with archaeological interest in order to identify how the environmental factors affect the molecular structure of type I collagen. In bone samples that proceed from an specific region with the same environmental conditions, the enthalpy value per unit mass was found to diminish exponentially with respect to the bone antiquity.

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Difference in thermal stability of type-I and type-III collagen from rat skin

Biochemical Journal ◽

10.1042/bj2030323 ◽

1982 ◽

Vol 203 (1) ◽

pp. 323-326 ◽

Cited By ~ 14

Author(s):

Carl Christian Danielsen

Keyword(s):

Thermal Stability ◽

Type I Collagen ◽

Type Iii Collagen ◽

Type I ◽

Neutral Salt ◽

Rat Skin ◽

Thermal Stabilities ◽

Type Iii ◽

Thermal Stability Of ◽

Salt Fractionation

Type-I and type-III collagens were obtained by differential salt fractionation of neutral-salt-soluble collagen from rat skin. Their thermal stabilities were determined by u.v. difference spectroscopy. The ‘melting’ temperature (Tm) in 5mm-acetic acid of type-III collagen was almost 2°C above that of type-I collagen. Intramolecular covalent cross-linking had no effect on the thermal stability.

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