What is Collagen? What is Collagen? By Dr Ananya Mandal, MD Collagen is a protein made up of amino-acids, which are in turn built of carbon, oxygen and hydrogen. Collagen contains specific amino acids – Glycine, Proline, Hydroxyproline and Arginine. Collagen makes up approximately 30% of the proteins within the body. These are tough and strong structures found all over the body: in bones, tendons and ligaments. Where is collagen found? In nature, collagen is found exclusively in animals, especially in the flesh and connective tissues of mammals. Collagen is a part of the connective tissue that in the skin helps in firmness, suppleness and constant renewal of skin cells. Collagen is vital for skin elasticity. Ligaments are another type of connective tissue that attach two bones and consequently hold the joints together. Tendons are similar but different type of tissue that attach the muscles to the bones. All of these tissues, the bones, ligaments, tendons and the skeletal muscles themselves, are made up of proteins. One of the most predominant proteins is called collagen.

Collagen is the main component of connective tissue, and is the most abundant protein in mammals, making up about 25% to 35% of the whole-body protein content. An atomic-force-microscopy image of collagen fibrils in a collagen fiber. Image Credit: UChicago Argonne LLC What does collagen do? Collagen helps to give strength to various structures of the body and also protects structures like the skin by preventing absorption and spreading of pathogenic substances, environmental toxins, micro - organisms and cancerous cells. Collagen protein is the cement that holds everything together. Collagen is also present in all the smooth muscle tissues, blood vessels digestive tract, heart, gallbladder, kidneys and bladder holding the cells and tissues together. Collagen is even the major component of the hair and nails. Aging and collagen With age, collagen production slows and the cells structures weaken. The skin gets thinner and is easier to damage, hair gets lifeless, skin sags and wrinkles, tendons and ligaments become less elastic, joints get stiff etc. Structure of collagen Collagen microscopically occurs in elongated fibrils.

It is mostly found in fibrous tissues such as tendon, ligament and skin, and is also abundant in cornea, bone, blood vessels, cartilage, intervertebral disc and the digestive tract. In muscle tissue, collagen serves as a major component of endomysium. 1 to 2% of the muscles are formed of collagen and around 6% of the total weight of muscles is formed of collagen. Gelatin used in food is collagen that has been irreversibly hydrolyzed. Molecular structure of collagen In the mid-1930’s collagen was first discovered to have a molecular structure. Nobel laureates Crick, Pauling, Rich and Yonath and others including Brodsky, Berman, and Ramachandran have been researching the structure of collagen and their possible functions. After several speculations of individual peptide chain, the final model that has been developed is the "Madras" model which provided an essentially correct model of the molecule's quaternary structure although this model still required some refinement. It is a triple-helical structure. Collagen is further packed into fibrillar collagen types with hexagional or quasi hexagonal shapes.

The packing may be 'sheet-like' or microfibrillar. The microfibrillar structure of collagen fibrils in tendon, cornea and cartilage has been directly imaged by electron microscopy. The microfibrillar structure of adult tendon was confirmed in 2006 by Fraser, Miller and Wess (amongst others). They found the D-periodic pentameric arrangement and termed it microfibril. Reviewed by April Cashin-Garbutt , BA Hons (Cantab) Collagen uploaded - Collagen is the main protein of connective tissue in Collagen uploaded Collagen uploaded - Collagen is the main protein of... SCHOOL View Full Document Collagen is the main protein of connective tissue in animals and the most abundant protein in mammals, making up approximately 25% of the total protein content in the human body. Function Collagen is a long, fibrous structural protein whose functions are quite different from those of globular proteins such as enzymes; tough bundles of collagen, collagen fibers, are a major component of the extracellular matrix that supports tissues and gives cells structure from the outside. Collagen is also found inside certain cells such as bone cells.

Collagen has great tensile strength, and is the main component ofcartilage, ligaments, tendons, bones and teeth. Along with soft keratin, it is well known for its responsibility for skin strength and elasticity, and its degradation leads to wrinkles that accompany aging. Collagen is often used as a cosmetic material to fill wrinkles. It is present in the cornea and lens of the eye in crystalline form. It is also used in cosmentic surgery and burns surgery.It also strengthens blood vessels and plays a role in the development of tissues. Composition and structure This preview has intentionally blurred sections. Sign up to view the full version. This is the end of the preview. Sign up to access the rest of the document. TERM Collagen Collagen Collagen Collagen is the main protein of connective tissue in animals and the most abundant protein in mammals, [1] making up about 25% of the total protein content.

Contents 9 Additional images Uses Collagen is one of the long, fibrous structural proteins whose functions are quite different from those of globular proteins such as enzymes ; 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, ligaments, tendons, bone and teeth. Along with soft keratin, it is responsible for skin strength and elasticity, and its degradation leads to wrinkles that accompany aging. It strengthens blood vessels and plays a role in tissue development. It is present in the cornea and lens of the eye in crystalline form. It is also used in cosmetic surgery and burns surgery. Industrial uses If collagen is partially hydrolyzed , the three tropocollagen strands separate into globular, random coils , producing gelatin , which is used in many foods, including flavored gelatin desserts . Besides food, gelatin has been used in pharmaceutical, cosmetic, and photography industries.

[2] Collagen and gelatin are poor-quality protein since they do not contain all the essential amino acids that the human body requires - they are not complete proteins . Manufacturers of collagen-based dietary supplements claim that their products can improve skin and fingernail quality as well as joint health. However, mainstream scientific research has not shown any evidence to support these claims. Individuals with problems in these areas are more likely to be suffering from some other underlying condition rather than protein deficiency. From the Greek for glue, kolla, the word collagen means "glue producer" and refers to the early process of boiling the skin and 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 bows about 1,500 years ago. The oldest glue in the world, carbon-dated as more than 8,000 years old, was found to be collagen — used as a protective lining on rope baskets and embroidered fabrics , and to hold utensils together; also in crisscross decorations on human skulls. [3] Collagen normally converts to gelatin, but survived due to the dry conditions.

Animal glues are thermoplastic , softening again upon reheating, and so they are still used in making musical instruments such as fine violins and guitars, which may have to be reopened for repairs — an application incompatible with tough, 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 ethanedial ) has been used to repair experimental incisions in rabbit lungs. [4] Medical uses 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. 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 ( Bovine spongiform encephalopathy ) 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 and New Zealand. porcine (pig) tissue is also widely used for producing collagen sheet for a variety of surgical purposes. due to the care in donor animal breeding and selection, as well as the technology used in the preparation of collagen from animal sources, the chance of immune reactions or disease transmission has been virtually eliminated.[citation needed] alternatives using the patient's own fat, hyaluronic acid or polyacrylamide gel are readily available. Collagens are widely employed in the construction of artificial skin substitutes used in the management of severe burns. These collagens may be derived from bovine, equine or porcine, and even human, sources and are sometimes used in combination with silicones , glycosaminoglycans, fibroblasts, growth factors and other substances. Collagen is also sold commercially as a joint mobility supplement. This lacks supportive research as the proteins would just be broken down into its base amino acids during digestion, and could go to a variety of places besides the joints depending upon need and DNA orders. Recently an alternative to animal-derived collagen has become available.

Although expensive, this human collagen, derived from donor cadavers, placentas and aborted fetuses, [5] may minimize the possibility of immune reactions. Composition and structure The structure of Collagen eluded scientist for decades. Many prominent scholars, including Nobel laureates like Watson and Crick and Linus Pauling were known to have been working on collagen structure when it was finally discovered. [6] The triple helical structure that is known to be correct in the essentials was proposed by G. N. Ramachandran and Gopinath Kartha in the year 1954. [7] [8] This proposed structure came to be known as the Madras helix. The tropocollagen or "collagen molecule" subunit is a rod about 300 nm long and 1.5 nm in diameter, made up of three polypeptide strands, each of which is a left-handed helix, not to be confused with the commonly occurring alpha helix, which is right-handed. These three left-handed helices are twisted together into a right-handed coiled coil , a triple helix or "super helix", a cooperative quaternary structure stabilized by numerous hydrogen bonds .

Tropocollagen subunits spontaneously self-assemble , with regularly staggered ends, into even larger arrays in the extracellular spaces of tissues. There is some covalent crosslinking within the triple helices, and a variable amount of covalent crosslinking between tropocollagen helices, to form the different types of collagen found in different mature tissues — similar to the situation found with the α-keratins in hair. Collagen's insolubility was a barrier to study until it was found that tropocollagen from young animals can be extracted because it is not yet fully crosslinked . Collagen fibrils are collagen molecules packed into an organized overlapping bundle. Collagen fibers are bundles of fibrils. A distinctive feature of collagen is the regular arrangement of amino acids in each of the three chains of these collagen subunits. The sequence often follows the pattern Gly -X- Pro or Gly-X- Hyp , where X may be any of various other amino acid residues. Gly-Pro-Hyp occurs frequently. This kind of regular repetition and high glycine content is found in only a few other fibrous proteins, such as silk fibroin.

75-80% of silk is (approximately) -Gly-Ala-Gly-Ala- with 10% serine — and elastin is rich in glycine, proline, and alanine (Ala), whose side group is a small, inert methyl. Such high glycine and regular repetitions are never found in globular proteins. Chemically-reactive side groups are not needed in structural proteins as they are in enzymes and transport proteins . The high content of Proline and Hydroxyproline rings, with their geometrically constrained carboxyl and (secondary) amino groups, accounts for the tendency of the individual polypeptide strands to form left-handed helices spontaneously, without any intrachain hydrogen bonding. Because glycine is the smallest amino acid, it plays a unique role in fibrous structural proteins. In collagen, Gly is required at every third position because the assembly of the triple helix puts this residue at the interior (axis) of the helix, where there is no space for a larger side group than glycine’s single hydrogen atom . For the same reason, the rings of the Pro and Hyp must point outward.

These two amino acids thermally stabilize the triple helix — Hyp even more so than Pro — and less of them is required in animals such as fish, whose body temperatures are low. In bone, entire collagen triple helices lie in a parallel, staggered array. 40 nm gaps between the ends of the tropocollagen subunits probably serve as nucleation sites for the deposition of long, hard, fine crystals of the mineral component, which is (approximately) hydroxyapatite , Ca5(PO4)3(OH), with some phosphate . It is in this way that certain kinds of cartilage turn into bone. Collagen gives bone its elasticity and contributes to fracture resistance. Types of collagen and associated disorders Collagen occurs in many places throughout the body. There are 28 types of collagen described in literature. Over 90% of the collagen in the body, however, are Collagens I, II, III, and IV.

A simple way to remember their general functions is: Collagen One - bONE (main component of bone) Collagen Two - carTWOlige (main component of cartilage) Collagen Three - reTHREEculate (main component of reticular fibers) Collagen Four - FLOOR - forms the basement membrane Collagen diseases commonly arise from genetic defects that affect the biosynthesis, assembly, postranslational modification, secretion, or other processes in the normal production of collagen. Type In addition to the above mentioned disorders, excessive deposition of collagen occurs in Scleroderma. Staining In histology, collagen is brightly eosinophilic (pink) in standard H&E slides. The dye methyl violet may be used to stain the collagen in tissue samples. The dye methyl blue can also be used to stain collagen and immunohistochemical stains are available if required. The best stain for use in differentiating collagen from other fibers is Masson's trichrome stain. Collagen is birefringent when stained with Sirius red F3B (C.I. 35782).

[9] Synthesis Collagen has an unusual amino acid composition and sequence: Glycine (Gly) is found at almost every third residue Proline (Pro) makes up about 9% of collagen Collagen contains two uncommon derivative amino acids not directly inserted during translation . These amino acids are found at specific locations relative to glycine and are modified post-translationally by different enzymes, both of which require vitamin C as a cofactor. Hydroxyproline (Hyp), derived from proline. Hydroxylysine , derived from lysine . Depending on the type of collagen, varying numbers of hydroxylysines have disaccharides attached to them. Collagen I formation Most collagen forms in a similar manner, but the following process is typical for type I: Inside the cell Three peptide chains are formed (2 alpha-1 and 1 alpha-2 chain) in ribosomes along the Rough Endoplasmic Reticulum (RER).

These peptide chains (known as preprocollagen) have registration peptides on each end; and a signal peptide is also attached to each Peptide chains are sent into the lumen of the RER Signal Peptides are cleaved inside the RER and the chains are now known as procollagen Hydroxylation of lysine and proline amino acids occurs inside the lumen. This process is dependent on Ascorbic Acid (Vitamin C) as a cofactor Glycosylation of specific hydroxylated amino acid occurs Triple helical structure is formed inside the RER Procollagen is shipped to the golgi apparatus, where it is packaged and secreted by exocytosis Outside the cell Registration peptides are cleaved and tropocollagen is formed by procollagen peptidase. Multiple tropocollagen molecules form collagen fibrils, and multiple collagen fibrils form into collagen fibers Collagen is attached to cell membranes via several types of protein, including fibronectin and integrin . Synthetic pathogenesis Vitamin C deficiency causes scurvy , a serious and painful disease in which defective collagen prevents the formation of strong connective tissue.

Gums deteriorate and bleed, with loss of teeth; skin discolors, and wounds do not heal. Prior to the eighteenth century, this condition was notorious among long duration military, particularly naval, expeditions during which participants were deprived of foods containing Vitamin C. In the human body, a malfunction of the immune system, called an autoimmune disease, results in an immune response in which healthy collagen fibers are systematically destroyed with inflammation of surrounding tissues. The resulting disease processes are called Lupus erythematosus, and rheumatoid arthritis, or collagen tissue disorders. [10] Many bacteria and viruses have virulence factors which destroy collagen or interfere with its production. Collagen in art Julian Voss-Andreae has created sculptures based on the collagen structure out of bamboo and stainless steel. His piece "Unraveling Collagen" is, according to the artist, a "metaphor for aging and growth" [11] [12] . See also Characterization of Collagen | Micromeritics Analysis Services Collagen is the main protein of connective tissue in animals and the most abundant protein in mammals, making up about 25% of the total protein content.

Collagen and collagen fibers have great tensile strength, and are the main component of fascia, cartilage, ligaments, tendons, bone, and teeth. Collagen is also partially responsible for skin strength and elasticity, and its degradation leads to wrinkles that accompany aging. As you would expect, there is much research currently underway to find new sources of collagen, as well as new applications. Micromeritics Analytical Services supports this research by measuring the particle size, surface area, porosity, density, and photomicrographs of collagen powder and collagen fibers. Collagen Collagen Helps Increase Energy And Endurance Helps Firm And Tone Muscless & Skin Easy To Mix, No Aftertaste Collagen Collagen is the main protein of connective tissue in animals and the most abundant protein in mammals, making up about 25% to 35% of the whole-body protein content. It is naturally found exclusively in metazoa, including sponges. In muscle tissue it serves as a major component of endomysium.

Collagen constitutes 1% to 2% of muscle tissue, and accounts for 6% of the weight of strong, tendinous muscles.The gelatin used in food and industry is derived from the partial hydrolysis of collagen. Collagen Uses Collagen is one of the long, fibrous structural proteins whose functions are quite different from those of globular proteins such as enzymes. 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, ligaments, tendons, bone and skin. Along with soft keratin, it is responsible for skin strength and elasticity, and its degradation leads to wrinkles that accompany aging. It strengthens blood vessels and plays a role in tissue development. It is present in the cornea and lens of the eye in crystalline form. It is also used in cosmetic surgery and burns surgery.

Hydrolyzed collagen can play an important role in weight management, as a protein, it can be advantageously used for its satiating power Collagen Medical uses 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. 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 (Bovine spongiform encephalopathy) 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 gel are readily available. Collagens are widely employed in the construction of artificial skin substitutes used in the management of severe burns.

These collagens may be derived from bovine, equine or porcine, and even human, sources and are sometimes used in combination with silicones, glycosaminoglycans, fibroblasts, growth factors and other substances. Collagen is also sold commercially as a joint mobility supplement. Because proteins are broken down into amino acids before absorption, there is no reason for orally ingested collagen to affect connective tissue in the body, except through the effect of individual amino acid supplementation. Recently an alternative to animal-derived collagen has become available. Although expensive, this human collagen, derived from donor cadavers, placentas and aborted fetuses, may minimize the possibility of immune reactions. Although it cannot be absorbed through the skin, collagen is now being used as a main ingredient for some cosmetic makeup. Collagen - New World Encyclopedia Collagen Next (Collation) Tropocollagen triple helix. Collagen is the main protein of connective tissue in animals and the most abundant protein in mammals , making up about 25 percent of the total protein content. Collagen involves the harmonization of three polypeptide chains into the form of a triple helix.

It is characterized by the regular arrangement of amino acids in each of the three chains, with regular repetition and high glycine content—with glycine found at almost every third residue. Under tension, the triple helix coils tight, resisting stretching, and making collagen valuable for structure and support, while giving bones some elasticity. There are at least 27 types of collagen (Zhao 2006). Humans creatively use collagen to make gelatin for use in foods, cosmetics, photography, and pharmaceuticals (when the three strands are hydrolyzed into random coils); for cosmetic surgery; to construct artificial skin ; and to make glue (collagen comes from the Greek word for glue, kolla, and essentially means "glue producer"). Contents The disease scurvy, traced to vitamin C (ascorbic acid) deficiency, results when defective collagen prevents the formation of strong connective tissue. This is tied to the fact that Vitamin C is a critical cofactor in the formation of collagen. Overview Collagen is common in many types of connective tissue , such as loose connective tissue, dense connective tissue, reticular connective tissue, bone , and cartilage .

Connective tissue is one of four primary body tissues of animals , the other three being muscle tissue (contain contractile filaments that move past each other and change the size of the cell), nervous tissue (forming the brain , spinal cord, and peripheral nervous system), and epithelium (covers organs and surface, including outside surface and inside cavities and lumen). Connective tissue is largely a category of exclusion rather than one with a precise definition, but all or most tissues in this category are similarly involved in structure and support. Blood, cartilage, and bone are usually considered connective tissue as well. Collagen is one of the long, fibrous structural proteins whose functions are quite different from those of globular proteins such as enzymes . 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 cartilage , ligaments , tendons, bone , and teeth. Along with soft keratin , it is responsible for skin strength and elasticity, and its degradation leads to wrinkles that accompany aging.

Collagen strengthens blood vessels and plays a role in tissue development. It is present in the cornea and lens of the eye in crystalline form. It is also used in cosmetic surgery and surgery for burns. Composition and structure The tropocollagen or "collagen molecule" subunit is a rod about 300 nm long and 1.5 nm in diameter. It is made up of three polypeptide strands, each of which is a left-handed helix, not to be confused with the commonly occurring alpha helix, which is right-handed. These three left-handed helices are twisted together into a right-handed coil, a triple helix, a cooperative structure stabilized by numerous hydrogen bonds . Tropocollagen subunits spontaneously self-assemble, with regularly staggered ends, into even larger arrays in the extracellular spaces of tissues. There is some covalent crosslinking within the triple helices, and a variable amount of covalent crosslinking between tropocollagen helices, to form the different types of collagen found in different mature tissues. This is similar to the situation found with the α-keratins in hair .

Collagen's insolubility was a barrier to its study until it was found that tropocollagen from young animals can be extracted because it is not yet fully crosslinked. Collagen fibrils are collagen molecules packed into an organized overlapping bundle. Collagen fibers are bundles of fibrils. Collagen has an unusual amino acid composition and sequence: Glycine (Gly) is found at almost every third residue (portion, or monomer, of larger molecule) Proline (Pro) makes up about 9% of collagen There are two uncommon derivative amino acids not directly inserted during translation of mRNA . They are found at specific locations relative to glycine and are modified post-translationally by different enzymes, both of which require vitamin C as a cofactor. Hydroxyproline (Hyp), derived from proline. Hydroxylysine, derived from lysine . Depending on the type of collagen, varying numbers of hydroxylysines have disaccharides attached to them. A distinctive feature of collagen is the regular arrangement of amino acids in each of the three chains of the collagen subunits.

The sequence often follows the pattern glycine -X- proline or glycine-X-hydroxyproline, where X may be any of various other amino acid residues. Gly-Pro-Hyp (glycine-proline-hydropxyproline) occurs frequently. This kind of regular repetition and high glycine content is found in only a few other fibrous proteins, such as silk fibroin. Approximately 75-80 percent of silk is Gly-Alanine-Gly-Alanine with 10 percent serine —and elastin is rich in glycine, proline, and alanine (Ala), whose side group is a small, inert methyl. Such high glycine and regular repetitions are never found in globular proteins. Chemically-reactive side groups are not needed in structural proteins as they are in enzymes and transport proteins. The high content of Pro and Hyp rings, with their geometrically constrained carboxyl and (secondary) amino groups, accounts for the tendency of the individual polypeptide strands to form left-handed helices spontaneously, without any intrachain hydrogen bonding. The triple helix tightens under tension, resisting stretching, making collagen inextensible.

Because glycine (Gly) is the smallest amino acid, it plays a unique role in fibrous structural proteins. In collagen, Gly is required at every third position because the assembly of the triple helix puts this residue at the interior (axis) of the helix, where there is no space for a larger side group than glycine’s single hydrogen atom . For the same reason, the rings of the Pro and Hyp must point outward. These two amino acids thermally stabilize the triple helix—Hyp even more so than Pro—and less of them is required in animals such as fish , whose body temperatures are low. In bone , entire collagen triple helices lie in a parallel, staggered array. Forty nanometer gaps between the ends of the tropocollagen subunits probably serve as nucleation sites for the deposition of long, hard, fine crystals of the mineral component, which is (approximately) hydroxyapatite, Ca5(PO4)3(OH), with some phosphate . It is in this way that certain kinds of cartilage turn into bone. Collagen gives bone its elasticity and contributes to fracture resistance. Types of collagen and associated disorders Collagen occurs in many places throughout the body.

There are 27 or 28 types of collagen described in literature (Zhao 2006). Collagen diseases commonly arise from genetic defects that affect the biosynthesis, assembly, postranslational modification, secretion, or other processes in the normal production of collagen. Type - Staining In histology (study of tissue), collagen is brightly eosinophilic (pink) in standard H&E slides. The dye methyl violet may be used to stain the collagen in tissue samples. The dye methyl blue can also be used to stain collagen and immunohistochemical stains are available if required. The best stain for use in differentiating collagen from other fibers is Masson's trichrome stain. Synthesis Collagen I formation Most collagen forms in a similar manner, but the following process is typical for type I: Inside the cell Three peptide chains are formed (2 alpha-1 and 1 alpha-2 chain) in ribosomes along the Rough Endoplasmic Reticulum (RER).

These peptide chains (known as preprocollagen) have registration peptides on each end; and a signal peptide is also attached to each Peptide chains are sent into the lumen of the RER Signal peptides are cleaved inside the RER and the chains are now known as procollagen Hydroxylation of lysine and proline amino acids occurs inside the lumen. This process is dependent on ascorbic acid (Vitamin C) as a cofactor Glycosylation of specific hydroxylated amino acid occurs Triple helical structure is formed inside the RER Procollagen is shipped to the golgi apparatus , where it is packaged and secreted by exocytosis Outside the cell Registration peptides are cleaved and tropocollagen is formed by procollagen peptidase. Multiple tropocollagen molecules form collagen fibrils, and multiple collagen fibrils form into collagen fibers Collagen is attached to cell membranes via several types of protein, including fibronectin and integrin Synthetic pathogenesis Vitamin C deficiency causes scurvy, a serious and painful disease in which defective collagen prevents the formation of strong connective tissue . Gums deteriorate and bleed, with loss of teeth; skin discolors, and wounds do not heal.

Prior to the eighteenth century, this condition was notorious among long duration military, particularly naval, expeditions during which participants were deprived of foods containing Vitamin C. In the human body, a malfunction of the immune system , called an autoimmune disease, results in an immune response in which healthy collagen fibers are systematically destroyed with inflammation of surrounding tissues. The resulting disease processes are called Lupus erythematosus, and rheumatoid arthritis, or collagen tissue disorders (Al-Hadithy et al. 1982). Many bacteria and viruses have virulence factors which destroy collagen or interfere with its production. Industrial and medical uses Industrial uses If collagen is partially hydrolyzed , the three tropocollagen strands separate into globular, random coils, producing gelatin, which is used in many foods, including flavored gelatin desserts. Besides food, gelatin has been used in pharmaceutical, cosmetic, and photography industries (GMAP 2005). Nutritionally, collagen and gelatin are considered poor quality protein because they lack adequate amounts of some of the essential amino acids . Some collagen-based dietary supplements are claimed to improve skin and fingernail quality and aid joint health, although mainstream scientific research in support of such claims is lacking.

Collagen historically has been a source of glue. From the Greek for glue, kolla, the word collagen, means "glue producer" and refers to the early process of boiling the skin and 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 bows about 1,500 years ago. The oldest glue in the world was found to be collagen—carbon dated as more than 8,000 years old—used as a protective lining on rope baskets and embroidered fabrics, to hold utensils together. and in crisscross decorations on human skulls (Walker 1998). Collagen normally converts to gelatin, but is considered to have survived in this case due to the dry conditions. Animal glues are thermoplastic, softening again upon reheating, and so they are still used in making musical instruments such as fine violins and guitars , which may have to be reopened for repairs: an application incompatible with tough, synthetic plastic adhesives, which are permanent. Medical uses Collagen has been widely used in cosmetic surgery and certain skin substitutes for burn patients.

The cosmetic use of collagens is declining because: There is a fairly high rate of allergic reactions causing prolonged redness and requiring inconspicuous patch testing prior to cosmetic use; Most medical collagen is derived from cattle , posing the risk of transmitting prion diseases like BSE alternatives using the patient's own fat or hyaluronic acid are readily available. Recently an alternative to bovine-derived collagen has become available. Although expensive, this recombinant human collagen seems to avoid immune reactions described above for collagen derived from livestock. Further, since the human collagen is produced via a yeast expression system, there is no risk of BSE contamination. Collagens are still employed in the construction of artificial skin substitutes used in the management of severe burns. These collagens may be bovine or porcine and are used in combination with silicones , glycosaminoglycans, fibroblasts, growth factors, and other substances. Collagen is also sold commercially as a joint mobility supplement. Additional images Action of lysyl oxydase (in French) References Al-Hadithy, H., D. A. Isenberg, I. E. Addison, A. H. Goldstone, and M. L. Snaith.

1982. Neutrophil function in systemic lupus erythematosus and other collagen diseases. Annals of the Rheumatic Diseases 41: 33-38. Gelatin Manufacturers Association of Asia Pacific (GMAP). 2005. Gelatin's advantages. Gelatin Manufacturers Association of Asia Pacific. Retrieved March 16, 2007. Walker, A. A. 1998. Oldest glue discovered. Archaeology, May 21, 1998. Retrieved March 16, 2007. Zhao, B. 2006. Collagen . DirectScience. Retrieved March 16, 2007. External links Collagens - Zimbio Collagens No articles yet. Overview A community portal about Collagens with blogs, videos, and photos. According to Wikipedia.org: Collagen is the main protein of connective tissue in animals and the most abundant protein in mammals, making up about 25% of the total protein content. It is one of the long, fibrous structural proteins whose functions are quite different from those...

more A community portal about Collagens with blogs, videos, and photos. According to Wikipedia.org: Collagen is the main protein of connective tissue in animals and the most abundant protein in mammals, making up about 25% of the total protein content. It is one of the long, fibrous structural proteins whose functions are quite different from those of globular proteins such as enzymes ; 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 cartilage, ligaments, tendons, bone and teeth. Along with soft keratin, it is responsible for skin strength and elasticity, and its degradation leads to wrinkles that accompany aging. It strengthens blood vessels and plays a role in tissue development. It is present in the cornea and lens of the eye in crystalline form. It is also used in cosmetic surgery and burns surgery. Featured Stories OVINEX™ - Premium Sheep Collagen soft tissue (skin, intestine) structural tissue (bone, inter-vertebral disc) The protein of collagen reduces as we age.

Our bodies lose collagen at a rate of about 1.5 percent per year from the age of 25. This means when we reach 45, we would have lost 30 percent of collagen. Today, with the growth of anti-aging medicine, there is tremendous interest in collagen. Mammalian Pig and cow have lots of cultural issues. With Australian patents and extraction technology, it allows us to extract collagen from the skin of sheep. Sheep (ovine) collagen faces no cultural or religion issues. Sheep collagen from Australia is sourced from animals that carry a “Disease Free Sheep” certification, the only such certification in the world. Bird This is a good warm-blooded source. The most common are chicken and duck. However, these animals are not genetically close to mammal. The other concern is disease as there is frequent outbreak of bird disease, the Avian Flu. Fish Toxic heavy metals in the ocean are global problems that are a growing threat to humanity. These fishes are contaminated to toxins such as metals, mercury, lead and arsenic. Moreover, fish is cold-blooded and not genetically close to human.

In the past, collagen has been manufactured from bovine (cow) and porcine (pig) skins through a process of acid solubilisation and enzymatic digestion to yield hydrolyzed Type I/III collagen. In recent times, bovine collagen has become less desirable due to safety issues surrounding Transmissible Spongiform Encephalopathies (BSE - Mad cow disease). Products produced from bovine and porcine sources are also not acceptable to all global cultures because of religious reasons. Now ovine collagen is available. Collagen Sources and their characteristics. COLLAGEN

Question: What is the main protein of connective tissue in animals and the most abundant protein in mammals, making up about 25% of the total protein content?
Answer: Collagen