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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.
a bond arising from the sharing of a hydrogen atom, covalently bound to a strongly electronegative element (for example, N, O, or a halogen), with another strongly electronegative element (for example, N, O, or a halogen). In substances of biologic importance, the most common hydrogen bonds are those in which H links N to O or N; such bonds link purines on one strand to pyrimidines on the other strand of nucleic acids, thus maintaining double-stranded structures as in the Watson-Crick helix.
Farlex Partner Medical Dictionary © Farlex 2012
hy·dro·gen bond(hī'drō-jen bond)
A bond arising from the sharing of a hydrogen atom, covalently bound to an electronegative element (e.g., N or O), with another electronegative element (e.g., N, O, or a halogen).
Medical Dictionary for the Health Professions and Nursing © Farlex 2012
hydrogen bondA bond in which a hydrogen atom is shared by two other atoms. The hydrogen is more firmly attached to one of these (which is called the hydrogen donor) than to the other (which is called the hydrogen acceptor). The acceptor has a relative negative charge, and, as unlike charges attract each other, a bond is formed to the hydrogen atom. Hydrogen bonds are weak and easily broken but occur extensively in biomolecules. The link between the bases in the two chains of DNA are hydrogen bonds. Adenine links to thymine by two hydrogen bonds, and guanine links to cytosine by three hydrogen bonds.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005
hydrogen bondthe attractive force between the hydrogen atom of one molecule and another molecule forming a noncovalent bond. These weak bonds are relevant to the biological function of particular compounds, being formed in the secondary structure of proteins and between complementary base pairs in NUCLEIC ACIDS.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005