A complex compound of glycomolecules linked to proteins, uronic acid and oligoelements (Cu, Zn, Fe, Ca) with rich biological functions that play a critical role for the sustaining of healthier tissues.
Biochemical investigation of the fluid we collect from snails proves it contains an heterogeneous compound of glycoconjugates, were we can find glycosaminoglycans, proteoglycans and glycoproteins. These are heterogeneous glyco molecules made of carbohydrate or sulfated sugar chains (glyco = sugar), globular soluble proteins, uronic acids and several oligoelements: (order:,:4:4: copper| zinc| calcium| iron).
Glycosaminoglycans (GAGs) are relatively large molecules composed of polysaccharide side chains attached to a core backbone of protein, forming a proteoglycan. Each polysaccharide side chain consists of a disaccharide repeat unit composed of hexosamine linked to uronic acids (either iduronic or glucuronic acid). The hexosamine is a glucosamine in heparin, and heparin sulfate and a galactosamine in dermatan sulfate (DS). The disaccharide units are heavily modified and the number of modifications allows for a large structural and functional diversity; it is the composition of the disaccharide side chains that defines the individual GAGs.
The disaccharides are often heavily sulfated and hence strongly negatively charged, and this may explain the pronounced ability of the GAGs to interact with proteins such as growth factors, enzymes, and chemokines. In the body, GAGs are present in mast cells (as heparin), in the extracellular matrix (ECM) and attached to cell surfaces. Clinically, GAGs are widely used for their anti-coagulating effects. Physiologically, the role of the GAGs has still to be fully determined. However, they are known to interact strongly with several growth factors, and therefore, GAGs are assumed to influence growth of normal as well as neoplastic (abnormal and cancer) cells and in the regulation of angiogenesis (growth of blood vessels) .
Order Out of Caos: The Function of Glycoconjugates
Proteoglycans, Glycoproteins and Glycosaminoglycans (GAGs) are active regulators of the cell's functions. They collaborate in cell-matrix communications and take a very important biological role in fibroblasts proliferation and in the differentiation and migration of all cells by effectively modulating the cell’s phenotype.
Fibroblasts are the cells in the basement membrane of the skin that give rise to all components of the extracellular matrix, in particular to collagen, elastin, glycosaminoglycans and proteoglycans in the skin matrix.
The basement membrane (BM) is a specialized form of extracellular matrix (ECM) and has recently been recognized as an important regulator of cell behaviour, rather than just a structural feature of tissues. The BM mediates tissue compartmentalization and sends signals to epithelial cells about the external microenvironment.
Proteoglycans are heterogeneous macromolecules consisting of a center protein and one or more covalently attached glycosaminoglycan chain. The biological function of proteoglycans result primarely from the structurally regent glycosaminoglycans emanating from the protein center of the molecule. A large number of different animal species include GAGs and mollusks are a very rich source of these glycomolecules or polysaccharides.
GAGs are often found in the extracellular matrix of vertebrate and invertebrate tissues. Structural investigation shows that GAGs in invertebrate animal species often include unusual variations of sulfate distribution and uronic acids.
The major glycoconjugate of the land snail liquid fluid is a glycosaminoglycan, with a peculiar structure when put next to other recognized glycosaminoglycans. It is secreted from granules inside the snail's structure and is localized on the external surface as a response to exposure of the snail to stress.
Why are glycosaminoglycans important for the skin?
Glycosaminoglycans are very important in regular animal development and in the prevention of many conditions; glycans appear to play a role as scaffolds that mediate interactions between cells and proteins.
Carbohydrates are indispensable to life. In their simple form, they serve as a primary energy source that sustains life. For the most part, anyway, carbohydrates exist not as simple sugars but as intrincated molecular conjugates, or glycans.
Glycans can have different shapes and sizes, from linear chains (polysaccharides) to highly branched molecules bristling with antennae-like arms. And although proteins and nucleic acids such as DNA posses traditionally brought a more scientific attention, glycans are also key to life. They are ever-present in nature, composing the complex sugar coat that encloses the cells of basically each and every organism and using the places among these cells. As a part of this so-named extracellular matrix, glycans, with their different chemical structures, play a very important role in transmmiting key biochemical signals into and among the cells. In this way, these sugars lead the cellular transmmition that is essential for regular cell and tissue development and physiological function.
GAGs form a vital component of connective tissues. GAG chains may be covalently attached to a protein to form proteoglycans.
Dermatan sulfate is a glycosaminoglycan found specially in skin, but also in blood vessels, heart valves, tendons, and lungs. Dermatan sulfate may have a part in coagulation, cardiovascular disease, carcinogenesis, infection, wound repair, and fibrosis.
Chondroitin sulfate is a sulfated glycosaminoglycan (GAG) composed of one chain of alternating sugars (N-acetyl-galactosamine and glucuronic acid). It’s mostly found knitted to proteins as part of a proteoglycan. A chondroitin chain can contain more than 100 individual sugars, and each of which can be sulfated in variable ways and quantities. Understanding the activities of such diversity in chondroitin sulfate and related glycosaminoglycans is a major goal of glycobiology. Chondroitin sulfate is a big structural part of cartilage and provides a lot of its tolerance to compression.
Complex sugars, or glycans, that are generally bound to proteins, coat the outer part of cells and get into the blanks among them. Vital in regular animal growing and in the prevention of a lot of conditions, glycans appear to play a role as scaffolds that mediate communications among cells and proteins.
Intrincated carbohydrates, molecules that are mostly vital for interaction in between cells, are are being studied systematically and shed light on the effects of the components of the snail secretions when used for skin care.
The most important paradigm of modern molecular biology is that biological data goes from DNA to RNA to protein. The strenght of this conception resides not only in its template-driven precision, but also in the ability to manipulate any one class of molecules based on recognition of another, and in the patterns of sequence homology and relatedness that prognosticate activity and reveal evolutionary relationships. With the expectedforthcoming finalization of the genomic catenations of humans and several other commonly analized model organisms, even more amazing gains in the study of biological systems are expected. Nonetheless, there’s often an inclination to take for correct the upcoming extension of the central paradigm: DNA to RNA to PROTEIN to CELL to ORGANISM.
In actual fact, making a cell requires two other major classes of molecules: lipids and carbohydrates. These molecules can work as intermediates in creating energy, as marking molecules, or as structural components. The structural main roles of carbohydrates become specially considerable in creating heterogeneous multicellular organs and organisms, that needs communication of cells with one another and with the matrix around it. Indeed, all cells and several macromolecules in nature carry a dense and heterogeneous array of covalently attached sugar chains (called oligosaccharides or glycans).
In some instances, these glycans can also be free-standing entities. Since most glycans are on the outer surface of cellular and secreted macromolecules, they are in a place to modulate or intercede a large collection of events in cell-cell and cell-matrix interactions vital to the development and action of a complex multicellular organism. They also are in a place to control interactions between organisms (e.g., between host and parasite).
Plus, simple, highly dynamic protein-bound glycans are abundant in the nucleus and cytoplasm, where they seem to work as managing switches.
During the initial part of this century, the chemistry, biochemistry, and biology of carbohydrates were very important subjects of research. However, when going through the the first years of the modern revolution in molecular biology, studies about glycans looked small next to those of other major classes of molecules. This was in large part due to their natural structural complexity, the difficulty in simply concluding their sequence, and the basis that their biosynthesis couldn’t be directly prognosticated from the DNA design.
The development of a variety of new technologies for exploring the structures of these sugar chains has given a big step for a new frontier of molecular biology that has been called glycobiology. This word was first coined in 1988 by Rademacher, Parekh, and Dwek to recognize the coming together of the traditional disciplines of carbohydrate chemistry and biochemistry with modern understanding of the cellular and molecular biology of glycans. The termn glycobiology has gainedlarge acceptance, with a major biomedical journal, a growing scientific society, and a Gordon Research Conference now using this name.
Defined in the larger way, glycobiology is the study of the morphology, biosynthesis, and biology of saccharides (sugar chains or glycans) that are largely expanded in nature. It’s one of the more rapidly areas in the biomedical sciences, with importance to basic research, biomedicine, and biotechnology. Indeed, several biotechnology, pharmaceutical, and laboratory supply business have invested heavily in the matter.
The area ranges from the chemistry of carbohydrates and the enzymology of glycan-modifying proteins to the functions of glycans in heterogeneous biological systems, and their manipulation by a variety of techniques.
Study in glycobiology needs a foundation not only in the nomenclature, biosynthesis, morphology, chemical synthesis, and activities of heterogeneous glycans, but also in the common disciplines of molecular genetics, cellular biology, physiology, and protein chemistry. This content provides an overview of the area of glycobiology, including a particular accentuation on the glycans of higher animal systems, about which the biggest amount is actually common. It’sassumed that who is reading has a basic knowledge in graduate-level chemistry, biochemistry, and cell biology.
In these passed years, important research of a class of linear glycans known as glycosaminoglycans (or GAGs for short), and particularly a sub-set known as HSGAGs, that are made up of heparan sulfate and its relative heparin have shed a good deal of light on the action of the snail secretions we use to elaborate the snail cream.
The complex snail secretions contribute to the correct assembling needed for healthy skin repair, skin regeneration and skin renewal.
Glycans help in the communication of fibroblast growth factor (FGF) with its receptor at the cell outer layer. The binding of growth factor to its receptor triggers a signaling cascade that ends up in the cell's nucleus, activating genes that control cellular proliferation.
An Heparan Sulfate GAG chain (HSGAG) can be characterized as a linear reiteration of approximately 10 to 100 disaccharide building blocks that, when put together, compose the basis of every sugar molecule. In its most basic form, every disaccharide unit consists of two chemically distinct monosaccharides (a uronic acid and a glucosamine) joined by a glycosidic bond. The chains could alter a great deal in their structural configuration because the disaccharide building blocks may be chemically mutated at a number of positions.
These modifications include the exclusion of the two-carbon acetyl groups at the amino position of the glucosamine portion and the inclusion of sulfate groups at especial different positions, also with distinctions in the stereochemical arrangement of bonds around precise carbons. Several combinations of these diverse chemical adjustments make it possible for even small chains to have a huge number of structural combinations. In fact, the ability for an large number of structural information to be embedded in a glycan passes that of nucleic acids or proteins.
Unlike the synthesis of DNA, RNA or proteins, glycan synthesis does not depend on a template that orders for the identical sequence of building blocks in a new chain, to be faith-fully replicated over and over again as an identical copy. Instead, GAGs are synthesized through the concerted action of a considerable repertoire of enzymes whose existence and relative activities diverge considerable. Inshort, HSGAG biosynthesis is a multi-step process with multiple enzyme players.
Most of the enzymes involved in HSGAG biosynthesis are now recognized, but precisely how the process of synthesis works is still in many areas an open question. We know just a few in regards to the ratio of enzymes or, even more primary, whether they act independently or co-operatively in a multienzyme complex. It is known that HSGAGs are fabricated within the cell in the membranes of the organelles known as the Golgi apparatus. Nearly all the enzymes involved making HSGAGs either span the organelle's membranes or are at least peripherally related with them. This arrangement essentially limits the equivalence of these enzymes to two dimensions inside a lipid lattice.
Even though the complete biochemical picture is not known yet, it is probable that the enzymes for HSGAG biosynthesis come together inside the Golgi membrane, possibly as the chain is being assembled. For the most part, glycans do not exist at the cell surface or in the extracellular matrix (ECM) as free-standing polymers. In exchange, they are assembled onto special proteins to form protein-glycan conjugates, or proteoglycans. With the exception of heparin, which is made as a free-standing sugar polymer, HSGAGs are commonly seeing in three major types of proteoglycans.
A major difference between these proteoglycans may be found in their unique arrangement dependent to the cell outer layer. In syndecans, the core proteins cross the cell membrane. Glypicans are also inserted into membranes, but by a lipid anchor connected to the core protein. Perlecans reside in the ECM. There is much proof that the specific composition of glycans linked to each core protein is not made at random.
Structure Defines Function. Proteoglycans are unique and structurally heterogeneous macromolecules. A clue to the action of HSGAG proteoglycans appears from the list of relevant proteins with which they connect in discrete space and temporal communications.
These proteins count lots of key growth factors and growth-factor receivers, proteins involved in in tissue and organ development and growing, others mixed in immune and inflammatory replies, some that comand cell adhesion, and so on. Like proteoglycans, the proteins that are related with them commonly reside outside cells, both close to cell membranes or floating in all the ECM. A lot of these proteins tour in the blood, where they are participants in methods like blood coagulation, wound repair and tissue repair.
The communications between glycans and the proteins they bind to reveal connections between structure and function. These interactions have commonly been ascribed just to the noncovalent electrostatic attaction between negatively charged sugars and positively charged proteins. A more exhaustive look, nonetheless, proves that lots of protein-glycan communications are as a matter of fact structurally selective. We now offer three samples of such specific communications—the binding of HSGAGs to antithrombin, to fibroblast growth factor (FBG) and to herpes simplex virus gD glycoprotein.
Sometimes, amazing structural determine commands the interaction between HSGAGs and proteins under some circumstancesimplicative of the so-named lock-and-key complementarity between enzymes and their substrates. The binding of heparin to antithrombin III (or ATIII) is a classic sample of such an interaction. ATIII is a protein that plays a key part in the cascade of steps that takes us to blood coagulation.
Clinicians have noticed the actions of heparin on this method since the early 1930s, at the moment when heparin was first used as an anticoagulant when doing a surgery. We actually known that in the moment when heparin unites to ATIII, this binding induces relevant change in the formation of the protein. On the other hands, this change greatly increases the inhibitory action that ATIII exerts on certain other proteins that commonly promote blood coagulation. A serial of experiments have proven that only a small segment inside heparin (which lives as a mixed group of molecules) actually binds to ATIII and leads its conformational change.
The minimal active binding sequence is a distinct pentasaccharide (that is, two-and-a-half disaccharide units). However, to trigger as much anticoagulation as could a full-length heparin molecule, a longer polysaccharide is needed, one that can at the same time bind to the protein thrombin as well as to antithrombin III. Although the HSGAG region that binds to thrombin doesn`t simce to need a precise line, its spacing relative to the ATIII-binding zone is very important.
This example illustrates two of the important points in regards to the interaction between proteins with HSGAGs, and probably other glycans. To begin with, the protein-binding region inside the polysaccharide isn’t randomly distributed along the chain; but, it is normally restricted to a small number of contiguous disaccharides no more than 100 that may conform its linear sequence. Second, a single glycan chain often contains two or more areas for protein binding. We can understand the glycan, in this way, as a molecular scaffold that helps in the favorable interaction of two or several protein partners.
Fibroblast growth factor (FGF) signalling elegantly pictures the concept of HSGAGs bringing proteins together. In particular, the glycans help in the interaction of fibro-blast growth factor with its receptor at the cell exterior. The binding of growth factor to its receptor triggers a signaling cascade that finishes in the cell's nucleus, turning on genes that modulate cellular development. To jumpstart this cascade, a receptor inside the cell membrane needs to go through a structural change, a change that occurs when one receptor interacts at the same time with a second receptor.
It looks like the fibroblast growth factor (FGF) molecules in the exterior of the cell (at least in the case of the growth factor known as FGF-2) have to themselves create a dimer, or pair, to unite two receptors on the cell exterior. Some investigations have proven that FGF signaling may not completely need the presence of the glycan; yet in this union of molecules glycans do serve as a type of glue, maintaining the complete complex attached in the proper assembling neccesary for maximal signal transduction.