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Their number and arrangement is called the secondary structure of the protein. Alpha helices are regular spirals stabilized by hydrogen bonds between the backbone CO group of one amino acid residue and the backbone NH group of the i+4 residue. The spiral has about 3.6 amino acids per turn, and the amino acid side chains stick out from the ...
A substance containing a glycosidic bond is a glycoside. The term 'glycoside' is now extended to also cover compounds with bonds formed between hemiacetal (or hemiketal) groups of sugars and several chemical groups other than hydroxyls, such as -SR (thioglycosides), -SeR (selenoglycosides), -NR 1 R 2 (N-glycosides), or even -CR 1 R 2 R 3 (C ...
Glycolipid. Glycolipids are lipids with a carbohydrate attached by a glycosidic (covalent) bond. [1] Their role is to maintain the stability of the cell membrane and to facilitate cellular recognition, which is crucial to the immune response and in the connections that allow cells to connect to one another to form tissues. [2]
Irreversible covalent – a chemical bond is formed in which the product is thermodynamically much more stable than the reactants such that the reverse reaction does not take place. Bound molecules are sometimes called a "molecular complex"—the term generally refers to non-covalent associations. [2]
A double bond between two given atoms consists of one σ and one π bond, and a triple bond is one σ and two π bonds. [8] Covalent bonds are also affected by the electronegativity of the connected atoms which determines the chemical polarity of the bond. Two atoms with equal electronegativity will make nonpolar covalent bonds such as H–H.
Monosaccharides can be linked together by glycosidic bonds, which can be cleaved by hydrolysis. Two, three, several or many monosaccharides thus linked form disaccharides, trisaccharides, oligosaccharides, or polysaccharides, respectively. Enzymes that hydrolyze glycosidic bonds are called "glycoside hydrolases" or "glycosidases".
A polar covalent bond is a covalent bond with a significant ionic character. This means that the two shared electrons are closer to one of the atoms than the other, creating an imbalance of charge. Such bonds occur between two atoms with moderately different electronegativities and give rise to dipole–dipole interactions. The ...
The two most common linkages in glycoproteins are N-linked and O-linked glycoproteins. [3] An N-linked glycoprotein has glycan bonds to the nitrogen containing an asparagine amino acid within the protein sequence. [4] An O-linked glycoprotein has the sugar is bonded to an oxygen atom of a serine or threonine amino acid in the protein. [4]