Collagen /ˈkɒlədʒɨn/ is the main structural protein
of the various connective tissues in animals. As the main component of
connective tissue, it is the most abundant protein in mammals,[3] making up
from 25% to 35% of the whole-body protein content. Collagen, in the form of
elongated fibrils, is mostly found in fibrous tissues such as tendons,
ligaments and skin, and is also abundant in corneas, cartilage, bones, blood
vessels, the gut, and intervertebral discs.
Collagen is composed of a triple helix, which generally consists of two
identical chains (α1) and an additional chain that differs slightly in its
chemical composition (α2).[25] The amino acid composition of collagen is
atypical for proteins, particularly with respect to its high hydroxyproline
content. The most common motifs in the amino acid sequence of collagen are
glycine-proline-X and glycine-X-hydroxyproline
So far, 28 types of collagen have been identified and described. The five
most common types are:
Collagen I: skin, tendon, vascular ligature, organs, bone (main
component of the organic part of bone)
Collagen II: cartilage (main component of cartilage)
Collagen III: reticulate (main component of reticular fibers), commonly
found alongside type I.
Collagen IV: forms basal lamina, the epithelium-secreted layer of the
basement membrane.
Collagen V: cell surfaces, hair and placenta
Cosmetic surgery
Collagen has been widely used in cosmetic surgery, as a healing aid for burn
patients for reconstruction of bone and a wide variety of dental,
orthopedic, and surgical purposes. Both human and bovine collagen is widely
used as dermal fillers for treatment of wrinkles and skin aging.[50] Some
points of interest are:
when used cosmetically, there is a chance of allergic reactions causing
prolonged redness; however, this can be virtually eliminated by simple and
inconspicuous patch testing prior to cosmetic use, and
most medical collagen is derived from young beef cattle (bovine) from
certified BSE-free animals. Most manufacturers use donor animals from either
"closed herds", or from countries which have never had a reported case of
BSE such as Australia, Brazil, and New Zealand.
porcine (pig) tissue is also widely used for producing collagen sheet
for a variety of surgical purposes.
alternatives using the patient's own fat, hyaluronic acid, or
polyacrylamide gels which are readily available.
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