Collagen/ja: Difference between revisions

==Characteristics==

Collagen is one of the long, [[fibrous protein|fibrous structural proteins]] whose functions are quite different from those of [[globular protein]]s, such as [[enzyme]]s. Tough bundles of collagen called ''collagen fibers'' are a major component of the [[extracellular matrix]] that supports most tissues and gives cells structure from the outside, but collagen is also found inside certain cells. Collagen has great [[tensile strength]], and is the main component of [[fascia]], [[cartilage]], [[ligament]]s, [[tendon]]s, [[bone]] and skin. Along with [[elastin]] and soft [[keratin]], it is responsible for skin strength and elasticity, and its degradation leads to [[wrinkle]]s that accompany [[aging]]. It strengthens [[blood vessel]]s and plays a role in [[biological tissue|tissue]] development. It is present in the [[cornea]] and lens of the eye in [[crystal]]line form. It may be one of the most abundant proteins in the fossil record, given that it appears to fossilize frequently, even in bones from the [[Mesozoic]] and [[Paleozoic]].

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===Uses===

[[file:Beretta Salami and Collagen Casing .jpg|right|150px|thumb|A salami and the collagen casing (below) it came in]]

Collagen has a wide variety of applications, from food to medical. In the medical industry, it is used in [[plastic surgery|cosmetic surgery]] and [[burn (injury)|burn surgery]]. In the food sector, one use example is in [[casing (sausage)|casings for sausages]].

If collagen is subject to sufficient [[denaturation (biochemistry)|denaturation]], such as by heating, the three tropocollagen strands separate partially or completely into globular domains, containing a different secondary structure to the normal collagen polyproline II (PPII) of [[random coil]]s. This process describes the formation of [[gelatin]], which is used in many foods, including flavored [[gelatin dessert]]s. Besides food, gelatin has been used in pharmaceutical, cosmetic, and photography industries. It is also used as a [[dietary supplement]], and has been advertised as a potential remedy against the ageing process.

From the Greek for glue, ''kolla'', the word collagen means "[[animal glue|glue]] producer" and refers to the early process of boiling the skin and [[tendon|sinews]] of horses and other animals to obtain glue. Collagen adhesive was used by Egyptians about 4,000 years ago, and Native Americans used it in [[bow (weapon)|bows]] about 1,500 years ago. The oldest glue in the world, [[radiocarbon dating|carbon-dated]] as more than 8,000 years old, was found to be collagen – used as a protective lining on rope baskets and [[embroidery|embroidered]] [[Textile|fabric]]s, to hold [[list of eating utensils|utensils]] together, and in crisscross decorations on [[human skull]]s. Collagen normally converts to gelatin, but survived due to dry conditions. Animal glues are [[thermoplastic]], softening again upon reheating, so they are still used in making [[musical instrument]]s such as fine violins and guitars, which may have to be reopened for repairs – an application incompatible with tough, [[chemical synthesis|synthetic]] plastic adhesives, which are permanent. Animal sinews and skins, including leather, have been used to make useful articles for millennia.

Gelatin-[[resorcinol]]-[[formaldehyde]] glue (and with formaldehyde replaced by less-toxic pentanedial and [[glyoxal|ethanedial]]) has been used to repair experimental incisions in rabbit [[lung]]s.