Navigation Links

Collagen is the main protein of connective tissue. It has great tensile strength, and is the main component of ligaments and tendons. It is responsible for skin elasticity, and its degradation leads to wrinkles that accompany aging. Collagen also fills out the cornea where it is present in crystalline form.

Collagen is the most abundant protein in mammals.


Features of collagen

Collagen has very interesting amino acid composition. It contains a lot of glycine and proline, as well as two amino acids that are not inserted directly by ribosomeshydroxyproline and hydroxylysine – the former composing a rather large percentage of the total amino acids. They are derivatised from proline and lysine in enzymatic processes of post translational modification, for which vitamin C is required. This is related to why vitamin C deficiencies can cause scurvy, a disease that leads to loss of teeth and easy bruising caused by a reduction in strength of connective tissue due to a lack of or defective collagen.

The white collagen that makes up the matrix of most connective tissue in mammals consists of inter-woven fibres of the protein collagen. The collagen fibres consist of globular units of the collagen sub-unit tropocollagen. Tropocollagen sub-units spontaneously arrange themselves under physiological conditions into staggered array structures stabilised by numerous hydrogen and covalent bonds. Tropocollagen sub-units are left-handed triple helices where each strand is, further, a right-handed helix itself. Thus, tropocollagen may be considered to be a coiled coil.

Another rare feature of collagen is its regular arrangement of amino acids in each of the alpha chains of the collagen sub-units. The sequence generally follows the pattern Gly-X-Y, where X is proline, and Y is proline or hydroxyproline. There are very few other proteins with such regularity. The inordinate number of Gly residues allows the otherwise sterically disallowed, tight coiling of each of the alpha chain subunits of tropocollagen, where there is a rise per turn of just 0.3 nm as opposed to the .36 nm of a regular Alpha helical coil. Hydroxylysine and hydroxyproline play important roles in the stabilisation of the tropocollagen globular structure as well as the final fibre shaped structure by forming covalent bonds. The resulting structure is called a collagen helix.

Types of collagen

Collagen occurs in many places throughout the body, and occurs in different forms known as types:

  • Type I collagen - This is the most abundant collagen of the human body. It is present in scar tissue , the end product when tissue heals by repair. It is found in tendons and the organic part of bone.
  • Type II collagen - Articular cartilage
  • Type III collagen - This is the collagen of granulation tissue , and is produced quickly by young fibroblasts before the tougher type I collagen is synthesised.
  • Type IV collagen - Basal lamina
  • Type V collagen - most interstitial tissue, assoc. with type I
  • Type VI collagen - most interstitial tissue, assoc. with type I
  • Type VII collagen - epithelia
  • Type VIII collagen - some endothelial cells
  • Type IX collagen - cartilage, assoc. with type II
  • Type X collagen - hypertrophic and mineralizing cartilage
  • Type XI collagen - cartilage
  • Type XII collagen - interacts with types I and III

See also

External link


(Date:9/22/2014)... Ill. Antarctic fishes that manufacture their own ... Ocean also suffer an unfortunate side effect, researchers ... their bodies resist melting even when temperatures warm. ... Proceedings of the National Academy of Sciences ... an undesirable consequence of the evolution of antifreeze ...
(Date:9/22/2014)... burn in Khabarovsk Krai, a territory occupying the coastline of ... plumes of smoke mark active fires. The smoke, which appears ... Sea of Okhotsk. Taiga and tundra are found ... central depression, and deciduous forests are the natural vegetation in ... in the summer, the 2014 wildfire season appears to be ...
(Date:9/22/2014)... may be at greater risk for stress-related diseases ... according to a new study by Brandeis University. ... trigger biological responses similar to the effects of ... is an important part of our body,s healing ... life-threatening diseases. , In a recently published ...
Breaking Biology News(10 mins):Study: Antifreeze proteins in Antarctic fishes prevent freezingand melting 2Study: Antifreeze proteins in Antarctic fishes prevent freezingand melting 3Obesity and stress pack a double hit for health 2
... in preserving and promoting a healthy cardiovascular system than ... researchers at the Medical College of Wisconsin in Milwaukee. ... the scientific journal Hypertension, was led by David D. ... medicine and physiology, and senior associate dean of research ...
... the red jungle fowl, but new research from Uppsala University ... more complicated than that. The researchers mapped ... found to their surprise that this genetic heredity derives from ... study is being published today in the Web edition of ...
... Option for Voluntary Use of Biometrics, WASHINGTON, ... Legal Workforce today applauded the introduction of,legislation viewed ... system and to helping prevent unauthorized,employment, a key ... The New Employee Verification Act (NEVA) introduced today ...
Cached Biology News:New study shows low-fat diets more likely to reduce risk of heart disease than low-carb diets 2Darwin was wrong about the wild origin of the chicken 2HR Initiative Endorses Bill to Create an Effective, Mandatory Federal Employment Verification System 2HR Initiative Endorses Bill to Create an Effective, Mandatory Federal Employment Verification System 3
Other biology definitionOther Tags