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Complex Carbohydrates Analysis: Enzymes, Kits, and Reagents

BioFiles 2007, 2.3, 1.

BioFiles 2007, 2.3, 1.

Introduction

Complex carbohydrates compose the most abundant class of biopolymers on earth. Because of their structural and functional diversity, they have found applications in biomedical, nutritional, textile, cosmetic and countless other industries.

The complex carbohydrates of the extracellular matrices such as hyaluronic acid and chondroitin sulfate are finding utility in antinflammatory and cell proliferation applications. In vivo, hyaluronic acid forms a coating around chondrocytes in articular cartilage and together with the proteoglycan, aggrecan, is responsible for the uptake and retention of water. The two major glycan components of aggrecan are chondroitin sulfate and keratan sulfate. Hyaluronic acid may also interact with cell surface receptors, such as CD44, involved in lymphocyte activation. The degradation products of hyaluronic acid may also interact with Toll-like receptors in macrophages. Heparan sulfate is commonly found as a component of cell surface proteoglycans. It is also found in the extracellular matrix. Heparan sulfate appears to have a broad range of biological functions including regulation of thrombosis, growth factor signaling, cell proliferation, adhesion and mobility. Depending on its morphology, location and ligands, heparan sulfate may inhibit or promote metastasis. Heparan sulfate is known to bind several protein ligands. Most notably, its binding affinity with antithrombin has been extensively utilized in the form of the anticoagulant, heparin.

Dextrans also help to decrease vascular thrombosis. By binding to the endothelium, platelets and red blood cells, dextrans impart an electronegative environment in the blood vessel resulting in a reduction of red blood cell aggregation and platelet adhesion to the vascular endothelium. In vivo, dextran solutions have also been used for blood volume expansion. Conversely, chitosan has the ability to induce clot formation. It is used in wound healing, particularly as a coating for bandages. Chitin may also aid in wound healing by accelerating collagen production. Chitosan is also used to enhance plant growth and may help plants resist fungal infection.

Chitin and starch are used as binders in the paper, dye, textiles and adhesives industries. Chitin and chitosan are also used as filtration aids, particularly in the waste water treatment industry. Chitosan aids in particulate aggregation as well as removal of phosphorus, metals, and grease from waste water. Modified agarose, chitin, starch and dextrans have been manipulated to produce media with controlled pore size for chemical separations. Beaded forms of cross-linked agarose and dextrans are the components of size exclusion, ion exchange and affinity chromatography media. Agarose and soluble starch are commonly used as electrophoresis media.

In the food industry, starches, aglinates, agarose, chitins, chitosans and pectins are used as gelling, thickening and encapsulating agents. Pectins and inulins are common components of dietary fiber supplements and may help to increase nutrient uptake. Pullulan is a common component of edible films.

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