A Note on Collagen Fibrous Proteins
Fibrous Proteins: One of the most abundant types of proteins, one that belongs to this type is collagen, which constitutes one third of the proteins of vertebrates, consists of a chain of three polypeptides which in turn is composed of 1000 amino acids linked by hydrogen bonds, forming a tight spiral molecules are packed into fibrils, and these in turn into larger fibers. The chains have as one of the amino acids glycine and abundance proline. Glycine is located in one of three amino acids, appears in the tendons, adjacent collagen molecules are linked by covalent bonds that were placed cross between neighboring amino acids and lysine. In a vertebrate, collagen is one of the tendons that attach muscles to bone, hazes consist of collagen fibers parallel very tough and not stretch. Other structures, however, such as leather, are formed by collagen fibrils that cause a network of overlapping sheets together. The cornea is a transparent roof made up of collagen. When collagen is boiled in water, the polymers are dispersed, resulting in shorter chains and causing the gelatin.
Other fibrous proteins include keratin, silk and elastin. Elastin is the elastic tissue of ligaments and part of the structure of the arteries and lungs. In the triple helix spiral in each chain is counterclockwise, but all three chains spiral in clockwise: The elasticity of elastin is due to the ability of molecules to reversibly unrolled, this protein is synthesized in tissue cells and secreted into the extracellular matrix.
Effectiveness Of Collagen
The term collagen (from kola Grier, meaning tail, ego nomen equivalent to produce) previously used only in specialized scientific areas, now it's used at the general public. It is therefore necessary to know well this protein in order to have a clear idea of its peculiarities and possibilities of application. To date, there have been numerous studies on collagen, but those relating to state on their participation in the mechanisms of aging are certainly the most important for the research that has come rushing into the field of cosmetics. The modification of collagen structure in the course of aging skin manifests itself at a loss of elasticity, reduced swelling of the underlying layers, leading to flaccid, shriveled appearance of old leather. This finding is also accompanied by other properties revealed by the fundamental studies carried out on collagen. Its reliability and its role in inflammatory phenomena, for example, put him in the forefront of biological substances available.
Soluble Collagen And Its Collection. Collagen in the form of insoluble fibers or fibrous aggregates, is the protein
Major constituent of the intercellular layers and fibrous connective tissues, which are major structural elements in the anatomy of vertebrates. As with protein, collagen is also present in abundance in other parts of the living. It is certain that collagen comprises between 30 and 60% of the total protein content of mammals, and over 30% of the total content of organic matter. The locations are primary protein in skin, bones and tendons, and dry weight, the bed of the corium of the skin (eg in the dermis), is composed of 90 to 95% collagen. However, the collagen fibers are not exclusively confined to those regions, but can also be found in every living tissue and organ.
The tissue was treated with dilute acids and in 1872 during a histological investigations, but Zacharias who was perhaps first noticed in 1900 that the tendons were swollen in dilute acid solutions came to be homogeneous, indicating that some substance had entered into solution. Previously, he had stated that all the collagen was insoluble. However, this phenomenon was not investigated until 1930 and was in France where, with more advanced techniques, it was shown that solutions of collagen in dilute acetic acid could be precipitated under certain conditions.
Later, in Russia, it was shown that extracts of collagen in citrate acid solutions containing a natural protein, and can be reconstituted by dialysis to give fibrous collagen.
A person showed that the soluble collagen could be obtained by extraction with acid citrate buffers from a pH 3 to pH 4.5 from any collagen and, particularly, in large quantities from young animals. This material was applied to the designation of procollagen; thereby trying to express the belief that acid-soluble collagen was the biological precursor of insoluble fibrous or collagen.
Commercially, the soluble collagen obtained from tissues by extraction with acid buffering or by dissolution in the course of alkaline or enzymatic processes. The methods of acid soluble collagen production are developed based on tonic for research purposes, but omitting some stages of these purified and accentuating the acidic character of the operation, production levels are achieved very acceptable.
General Properties: The native collagen has very specific properties not found in the degradation products, ie gelatin.
The biochemical reactivity of native collagen comes essentially from the telopeptide of the extremities of the polypeptide chain, that of a party and, secondly, its own structure.
The films prepared from native collagen solutions are very resilient.
Gelatin solutions by evaporation, tend generally to spray and they sometimes provide very fragile films.
Native collagen films adhere strongly to the cornified layers of human hypodermis and have a great power of water retention.
Extended native collagen on the skin does contain an element of smoothing on dry skin, diminishing the appearance of wrinkled skin and exfoliates old.
Formulation: Native collagen solutions can be added to cosmetic emulsions dispersions of ionic or nonionic acid in doses ranging from 5 to 10%.
Incompatibilities: The soluble collagen is incompatible with the. heat, light tannins and a very alkaline pH
Collagen formation: Phase intra-fibroblastic: From the Pro-collagen structure, form all types of collagen.
Phase extra-fibroblastic: At the start of fibroblast pro-collagen molecules undergo the action of two proteases whose cofactor is calcium, which break the bonds of the peptides of extension:
* The pro-collagen aminopeptidase that releases the semi-helical portion.
* The procollagen carboxypeptidase that releases the globular peptide. The molecule is called a trope-derived collagen. This basic molecule is presented in the form of rigid rod composed of three polypeptide chains coiled into a super-helix.
In the extremities of the molecule are amorphous polypeptide sequences called telopeptides.
The trope-collagen molecules spontaneously organize themselves through hydrogen bonds and hydrophobic electrostatic to form microfibrils. The stability of the first system is weak and its structure is still reversible. At this stage we can speak of native neutral-soluble collagen, it is possible to solubilize the molecule in a saline solution at neutral pH.
Maturation
At the level of the telopeptides establishing covalent bonds between the two polypeptide chains:
a) compact domain, b) Triple helix short (10-12 mm), c) telopeptide d) globular domain.
- The aldol-type intramolecular bridges connecting the chains of the same molecule.
- Intermolecular covalent bonds formed collagen fibers.
The maturation process leads to the crosslinking of collagen, resulting in insolubilization of the fibers. This is called the fibrous soluble native collagen
. Thus we find in the body simultaneously:
- Native neutral-soluble collagen
- Acid-soluble collagen (in the process of crosslinking).
- Fibrous insoluble native collagen
Based on these different solubilities collagens are classified as raw materials used in the production of dermal products.
Types Of Collagen
Have been described various genetically distinct collagen types, which can be classified into three groups according to their biochemical and morphological description:
Over Collagen
Collagen type I
Formed by the association in a triple helix of two identical polypeptide chains and genetically distinct a chain (a 1 I) 2 and 2 I. Its organization is supramolecular fibrils. It is found in all connective tissues and bone level totalitarian and dentin.
Collagen type II
It has fine supramolecular organization in fibrils. It lies at the level of cartilage and eye vitreous.
Collagen type III
Formed by the association in a triple helix of polypeptide chains identical (1 III) 3.
This collagen has cysteine residues that allow formation of disulfide bonds within the helix. Its supramolecular organization is fine fibrils forming a fine reticular network. This collagen associated with collagen type I is found in most connective tissue.
Collagen type IV
Formed by two different polypeptide chains and a 2 IV 1 IV whose molecular composition has not yet been clarified.
Areas has collagenous and non-collagenous areas, because of its low amount of glycine provides areas not organized at the helical portion. The collagen found in basement membranes.
Collagen type V
Composed of three polypeptide chains to 1 V to 2 V, 3 V The molecular composition of the V chain is yet to be defined.
It has tips collagen structure does not allow very stable partnerships.
It is located in the pericellular and in association with interstitial collagen fibers.
New Collagen
Collagen type I trimer embryonic formed by three chains to I.
Collagen type VI "intima collagen"
Consisting of three different polypeptide chains "short chain", 1 (VI) or SC1, 2 (VI) or SC 2 and 3 (VI) or SC3. They are forming a triple helix of short length.
Collagen type VII collagen LC "
Composed of three polypeptide chains LC (long chains). They are forming a triple helix of long length.
Collagen type VIII or endothelial collagen "
Formed by three protein chains EC1, EC2, EC and non-collagenous sequences.
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