Navigation Links
Collagen


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.

Contents

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:12/19/2014)... 18, 2014 Research and Markets ( http://www.researchandmarkets.com/research/86ncd6/micro_market ) ... North America Perimeter Security Systems Market" report to their ... The North American perimeter security market is estimated to grow ... the U.S. market holds a larger share in this market, ...
(Date:12/17/2014)... FORT BELVOIR, Va. , Dec. 15, 2014 ... make it easier to detect and prevent counterfeit microcircuits ... the agency started performing an in-house microcircuit anti-counterfeit initiative ... of purchased microcircuits while increasing their reliability throughout the ...
(Date:12/17/2014)... 16, 2014  Automation is fundamentally transforming the travel experience ... borders. Over the past decade, ePassports, biometric readers, and ... process through border control via eGates and Automated Passport ... seaports, and land borders across the globe. ...
Breaking Biology News(10 mins):Micro Market Monitor: North America Perimeter Security Systems Market (Intrusion Detection Sensor, Video Surveillance, Communication/Alarm and Notification, Access Control System) 2Micro Market Monitor: North America Perimeter Security Systems Market (Intrusion Detection Sensor, Video Surveillance, Communication/Alarm and Notification, Access Control System) 3Defense Logistics Agency Launches DNA Marking Capability to Strengthen Microcircuit Supply Chain 2Defense Logistics Agency Launches DNA Marking Capability to Strengthen Microcircuit Supply Chain 3Automated Border Control (ABC) Transforms the Global Travel Experience With More Than 2500 ABC eGates and APC Kiosks Deployed In Airports, Seaports, and Land Borders Worldwide 2
... mysterious island that moves through time. Travelers in search ... fiction television show "Lost," but it also describes a ... students. Iris Totten, an associate professor of geology ... professor of geology at University of Missouri at Kansas ...
... A first of its kind study examining the effects of ... cause abnormal brain development in children. The research is published ... , the medical journal of the American Academy of Neurology. ... women of childbearing age, leading to an increasing number of ...
... are less likely to use folic acid supplements before ... immigrated to the country, according to a new study ... with Statistics Canada, Health Canada and the University of ... estimates of pre-pregnancy folic acid use in Canada. ...
Cached Biology News:K-State using Second Life island to help high school students learn earth science 2Prenatal meth exposure linked to abnormal brain development 2Immigrant women may be at higher risk of having a baby with a birth defect 2
Other biology definitionOther Tags