covalent bond

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the linkage between atoms or radicals of a chemical compound, or the symbol representing this linkage and indicating the number and attachment of the valencies of an atom in constitutional formulas, represented by a pair of dots or a line between atoms, e.g., H—O—H, H—C≡C—H or H:O:H, H:C:::C:H.
coordinate covalent bond a covalent bond in which one of the bonded atoms furnishes both of the shared electrons.
covalent bond a chemical bond between two atoms or radicals formed by the sharing of a pair (single bond), two pairs (double bond), or three pairs of electrons (triple bond).
disulfide bond a strong covalent bond, —S—S—, important in linking polypeptide chains in proteins, the linkage arising as a result of the oxidation of the sulfhydryl (SH) groups of two molecules of cysteine.
high-energy phosphate bond an energy-rich phosphate linkage present in adenosine triphosphate (ATP), phosphocreatine, and certain other biological molecules. On hydrolysis at pH 7 it yields about 8000 calories per mole, in contrast to the 3000 calories yielded by phosphate esters. The bond stores energy that is used to drive biochemical processes, such as the synthesis of macromolecules, contraction of muscles, and the production of the electrical potentials for nerve conduction.
high-energy sulfur bond an energy-rich sulfur linkage, the most important of which occurs in the acetyl-CoA molecule, the main source of energy in fatty acid biosynthesis.
hydrogen bond a weak, primarily electrostatic, bond between a hydrogen atom bound to a highly electronegative element (such as oxygen or nitrogen) in a given molecule, or part of a molecule, and a second highly electronegative atom in another molecule or in a different part of the same molecule.
ionic bond a chemical bond in which electrons are transferred from one atom to another so that one bears a positive and the other a negative charge, the attraction between these opposite charges forming the bond.
peptide bond the —CO—NH— linkage formed between the carboxyl group of one amino acid and the amino group of another; it is an amide linkage joining amino acids to form peptides.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.
References in periodicals archive ?
Nevertheless, the lipase covalently immobilized on the sol-gel showed a much longer half-life than that of the lipase of Aspergillus niger (obtained from pumpkin seed SSF) encapsulated on a sol-gel ([t.sub.1/2] = 13.6h at 45[degrees]C) (Zubiolo et al., 2014) and the lipase of Candida antarctica immobilized on a sol-gel by covalent bonding ([t.sub.1/2] =1.9h at 40[degrees]C) (Yang et al., 2010).
After setting out the structure and spectra of DNA, they survey interactions by class of drugs, among them intercalating, covalent bonding, and metal containing.
Processing requires the pre-attachment through covalent bonding of capture molecules such as antibodies to the nanowire.
With the recent development of a reactive potential that models both covalent bonding and intermolecular interactions, we have performed molecular dynamics simulations to model the kev bombardment of a benzene crystal with normal incident 0.300 keV Xe atoms.
In this new method, the surface of the cellulosic fibers is modified by silane grafting (covalent bonding) using benzoyl peroxide as a catalyst.
Their topics include types of chemical reactions and solution stoichiometry, atomic structure and periodicity, covalent bonding: orbitals, solubility and complex ion equilibria, and the representative elements.
So that the above problem may be overcome, the enzyme may be immobilized by physical adsorption, covalent bonding, ionic interactions or encapsulation (DALLA-VECCHIA et al., 2004; UYANIK et al., 2011).
With the use of silane coupling agent, however, this type of hydrogen bonding at the interface is changed to strong covalent bonding, which would enhance the durability of bond strength under water exposure.
The coating will firmly bond with touch screen glass by covalent bonding mechanism.
Finally, the covalent bonding of the NAD+ cofactor and the lactate dehygroenase enzyme upon the synthesized nanocomposite led to the production of a fully integrated bio-sensor for lactate analysis.