Collagen Structure & Function: Difference between revisions
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The shape and structural properties of a native collagen molecule are established by its triple-helical domain(s). In classical collagen molecules a single triple-helical domain is observed to compose close to 95% of the molecule <ref>PMID: 19853297</ref>. However there are also other types of collagens that have been shown to comprise of multiple triple-helical domains which only account for a fraction of the molecule's overall mass. | The shape and structural properties of a native collagen molecule are established by its triple-helical domain(s). In classical collagen molecules a single triple-helical domain is observed to compose close to 95% of the molecule <ref>PMID: 19853297</ref>. However there are also other types of collagens that have been shown to comprise of multiple triple-helical domains which only account for a fraction of the molecule's overall mass. | ||
The triple-helical domain of collagens consist of three distinct α-chains and earns collagen the name "tropocollagen". Each of these chains contain a characteristic L-handed amino acid sequence of polyproline, often termed as polyproline type II helix <ref>PMID: 19344236</ref>. The proper folding of each of these chains requires a glycine residue to be present in every third position in the polypeptide chain. For example, each α-chain is composed of multiple triplet sequences of of Gly-Y-Z in which Y and Z can be any amino acid. Y is commonly found as proline and Z as hydroxyproline. The presence of hydroxyproline in the Y position contributes to the stability of the helical form. | The triple-helical domain of collagens consist of three distinct α-chains and earns collagen the name "tropocollagen".<ref name="collalike">PMID:7695699</ref>. Each of these chains contain a characteristic L-handed amino acid sequence of polyproline, often termed as polyproline type II helix <ref>PMID: 19344236</ref>. The proper folding of each of these chains requires a glycine residue to be present in every third position in the polypeptide chain. For example, each α-chain is composed of multiple triplet sequences of of Gly-Y-Z in which Y and Z can be any amino acid. Y is commonly found as proline and Z as hydroxyproline. The presence of hydroxyproline in the Y position contributes to the stability of the helical form. | ||
These three chains are then twisted around one another in a rope-like manner to produce the overall tightly packed triple-helical form of the molecule. The interaction of α-chains is stabilized via interchain hydrogen bonding making the molecule fairly resistant to attack by other molcules. This hydrogen bonding occurs when the amino group (NH) of a glycine residue forms a peptide bond with the carbonyl (C=0) of an adjacent residue. The overall molecule is approxiametly 300nm long and 1.5-2nm in diameter .<ref name="collalike">PMID:7695699</ref>. | These three chains are then twisted around one another in a rope-like manner to produce the overall tightly packed triple-helical form of the molecule. The interaction of α-chains is stabilized via interchain hydrogen bonding making the molecule fairly resistant to attack by other molcules. This hydrogen bonding occurs when the amino group (NH) of a glycine residue forms a peptide bond with the carbonyl (C=0) of an adjacent residue. The overall molecule is approxiametly 300nm long and 1.5-2nm in diameter.<ref name="collalike">PMID:7695699</ref>. | ||
Revision as of 12:13, 31 March 2010
CollagenCollagen
| Please do NOT make changes to this Sandbox until after April 23, 2010. Sandboxes 151-200 are reserved until then for use by the Chemistry 307 class at UNBC taught by Prof. Andrea Gorrell. |
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| 1cag, resolution 1.85Å () | |||||||
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| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
IntroductionIntroduction
Collagen is a member of a family of naturally occurring proteins. It is one of the most plentiful proteins present in mammals and it is responsible for performing a variety of important biological functions, most importantly structural ones. It is present in large quantities in connective tissue and provides tendons and ligaments with tensile strength and skin with elasticity. It often works in conjuction with other important proteins such as keratin and elastin.
Molecular StructureMolecular Structure
The shape and structural properties of a native collagen molecule are established by its triple-helical domain(s). In classical collagen molecules a single triple-helical domain is observed to compose close to 95% of the molecule [1]. However there are also other types of collagens that have been shown to comprise of multiple triple-helical domains which only account for a fraction of the molecule's overall mass.
The triple-helical domain of collagens consist of three distinct α-chains and earns collagen the name "tropocollagen".[2]. Each of these chains contain a characteristic L-handed amino acid sequence of polyproline, often termed as polyproline type II helix [3]. The proper folding of each of these chains requires a glycine residue to be present in every third position in the polypeptide chain. For example, each α-chain is composed of multiple triplet sequences of of Gly-Y-Z in which Y and Z can be any amino acid. Y is commonly found as proline and Z as hydroxyproline. The presence of hydroxyproline in the Y position contributes to the stability of the helical form.
These three chains are then twisted around one another in a rope-like manner to produce the overall tightly packed triple-helical form of the molecule. The interaction of α-chains is stabilized via interchain hydrogen bonding making the molecule fairly resistant to attack by other molcules. This hydrogen bonding occurs when the amino group (NH) of a glycine residue forms a peptide bond with the carbonyl (C=0) of an adjacent residue. The overall molecule is approxiametly 300nm long and 1.5-2nm in diameter.[2].
The image on the right-hand side has each side chain colored a different color to shown how each individual interact with the others to form the overall molecule. The
have also been illustrated to point out their positions in the triple-helix.
.jpg)
FunctionFunction
There are currently close to 30 different types of collagen that have been identified [4]. The most abundant type of collagen present in the human body is that of Type I with significant amounts of Type II,III and IV also accounted for.
- Collagen I- found in bones,tendons,organs
- Collagen II- found mainly in cartilage
- Collagen III- found mainly in reticular fibres
- Collagen IV- found in the basement membrane of cell membranes
- Collagen V- found in hair
Collagen-Related DisordersCollagen-Related Disorders
There are many types of disorders associated with collagen.These disorders typically occur as a result of improper folding of these molecules and occasionally due to a particular amino acid substitution.[2]. These include:
- Elhers-Danlos Syndrome (IV)
- Alport Syndrome (IV)
- Osteogenesis imperfecta (I)
- Chondrodysplasias (II)
- Atopic Dermatitis (III)
ReferencesReferences
- ↑ Yamazaki CM, Kadoya Y, Hozumi K, Okano-Kosugi H, Asada S, Kitagawa K, Nomizu M, Koide T. A collagen-mimetic triple helical supramolecule that evokes integrin-dependent cell responses. Biomaterials. 2010 Mar;31(7):1925-34. Epub 2009 Oct 22. PMID:19853297 doi:10.1016/j.biomaterials.2009.10.014
- ↑ 2.0 2.1 2.2 Bella J, Eaton M, Brodsky B, Berman HM. Crystal and molecular structure of a collagen-like peptide at 1.9 A resolution. Science. 1994 Oct 7;266(5182):75-81. PMID:7695699
- ↑ Shoulders MD, Raines RT. Collagen structure and stability. Annu Rev Biochem. 2009;78:929-58. PMID:19344236 doi:10.1146/annurev.biochem.77.032207.120833
- ↑ Koide T. Designed triple-helical peptides as tools for collagen biochemistry and matrix engineering. Philos Trans R Soc Lond B Biol Sci. 2007 Aug 29;362(1484):1281-91. PMID:17581806 doi:10.1098/rstb.2007.2115