Definitions

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. (biochemistry) The reaction of a saccharide with a hydroxy or amino functional group to form a glycoside; especially the reaction with a protein or lipid to form a glycoprotein or glycolipid.

Etymologies

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Examples

  • Sugar triggers a process called glycosylation, which causes collagen to cross-link, with the result that the skin becomes stiff, inflexible, and discolored.

    THE HIGH SCHOOL REUNION DIET

  • Simply, glycosylation occurs when sugar molecules glucose floating around in our blood attach to protein molecules, diminishingtheir effectiveness and causing inflammation.

    You Staying Young

  • In addition, their scientists found the second and third cases in the world of a condition known as congenital disorder of glycosylation type 2B, which causes a range of severe malformations and cognitive problems.

    In pursuit of diseases that have no name

  • Nonenzymatic glycosylation of milk proteins occurs during heat treatment (Maillard reaction), leading to significant changes in the 3-dimensional structure of these proteins.

    Allegic Reactions from Lactose in Dry Powder Asthma Inhalers

  • Advanced glycosylation end products and nutrition—a possible relation with diabetic atherosclerosis and how to prevent it.

    The UltraMind Solution

  • The authors of the second paper admit that “other variables … influence the binding avidity (preference), such as type of SA (sialic acid of the receptor site) and glycosylation and sialylation of the hemagglutinin close to the receptor binding site. ” These factors all vary obviously and there are other variables in the equation as well including the status of specific areas of the immune system.

    Think Progress » An Inconvenient Truth and An Intolerable Summer

  • MG is a highly toxic glycating agent and a major source of protein advanced-glycosylation end-products AGEs.

    The low-fat diet cascade | The Blog of Michael R. Eades, M.D.

  • While it sounds like something you order up at Jiffy Lube for $39.95, glycosylation is one of the best examples of a biochemicalprocess that has dramatic physical effects.

    You Staying Young

  • In your lungs: The glycosylation of collagen results in abnormal recoil of the elastic tissue, so you have trouble getting the air out aswell as in.

    You Staying Young

  • In the skin: With the glycosylation of collagen, the collagen in your skin becomes less elastic and sliffer than a happy-hour martini.

    You Staying Young

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  • Glycosylation is the enzymatic process by which polysaccharides (sugars) are attached to certain proteins. It is a type of post-translational modification, which is site-specific, occurring only at certain motifs (amino-acid sequences) in the polypeptide chain of the target protein.

    There are two main types of glycosylation, N-linked and O-linked, depending on the binding site in the target protein. N-linked glycosylation occurs almost exclusively in eukaryotic proteins (most prokaryotic organisms are incapable) where it usually occurs after protein assembly, but before the protein folds to its final three-dimensional conformation. In many cases, glycosylation is a necessary prerequisite for correct folding of the protein.

    O-linked glycosylation occurs at a later stage during protein processing, probably in the Golgi apparatus. This is the addition of N-acetyl-galactosamine to serine or threonine residues, followed by other carbohydrates, such as galactose and sialic acid.

    Although the exact sequence of enzymatic reactions is often poorly characterized, initial linking of large branched carbohydrate molecules, with subsequent enzymatic pruning, appears to be the norm.

    Glycosylation is a process which yields variable results - that is, both the number and the nature of sugars attached can vary from one protein molecule to the next. Thus, a protein with four potential glycosylation loci may end up with anywhere from zero to four being occupied and the exact structure of the attached sugars can vary both across different loci within the same molecule and across different molecules.

    This potential for variable glycosylation patterns is usually referred to as microheterogeneity. It represents a significant challenge, for example, in the manufacture, by recombinant DNA technology (genetic engineering) of proteins for therapeutic use. While it is (relatively) straightforward to ensure purity and integrity of the amino-acid sequence constituting the target protein, control of the enzymatic processes effecting the post-translational glycosylation is notoriously difficult.

    The importance of overcoming this difficulty is directly related to the importance of the role that the glycosylation pattern plays in determining the activity of the protein. Even in cases where the exact nature of the final glycosylation structures has no direct effect on activity, it may still be important to understand (and control) the glycosylation pattern, which could still influence such properties as the pharmacokinetic behavior of the protein after dosing.

    December 13, 2008