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Bifurcated H-bond systems are common in alpha-helical transmembrane proteins between the backbone amide C=O of residue i as the H-bond acceptor and two H-bond donors from residue i + 4: the backbone amide N−H and a side-chain hydroxyl or thiol H +. The energy preference of the bifurcated H-bond hydroxyl or thiol system is -3.4 kcal/mol or -2. ...
Suffixes can be combined, as in methylidyne (triple bond) vs. methylylidene (single bond and double bond) vs. methanetriyl (three double bonds). There are some retained names, such as methylene for methanediyl, 1,x- phenylene for phenyl-1,x-diyl (where x is 2, 3, or 4), [ 5 ] carbyne for methylidyne, and trityl for triphenylmethyl.
Double bonds are shorter than single bonds with an average bond length of 1.33 Å (133 pm) vs 1.53 Å for a typical C-C single bond. [ 7 ] Each carbon atom of the double bond uses its three sp 2 hybrid orbitals to form sigma bonds to three atoms (the other carbon atom and two hydrogen atoms).
In contrast to NH 3, NF 3 has a much lower dipole moment of 0.234 D. Fluorine is more electronegative than nitrogen and the polarity of the N-F bonds is opposite to that of the N-H bonds in ammonia, so that the dipole due to the lone pair opposes the N-F bond dipoles, resulting in a low molecular dipole moment. [6]
For example, residue i may form hydrogen bonds to residues j − 1 and j + 1; this is known as a wide pair of hydrogen bonds. By contrast, residue j may hydrogen-bond to different residues altogether, or to none at all. The hydrogen bond arrangement in parallel beta sheet resembles that in an amide ring motif with 11 atoms.
The general formula is R−SO 2 NR'R" or R−S(=O) 2 −NR'R", where each R is some organic group; for example, "methanesulfonamide" (where R = methane, R' = R" = hydrogen) is CH 3 SO 2 NH 2. Any sulfonamide can be considered as derived from a sulfonic acid by replacing a hydroxyl group ( −OH ) with an amine group.
Silanes are saturated chemical compounds with the empirical formula Si x H y. They are hydrosilanes, a class of compounds that includes compounds with Si−H and other Si−X bonds. All contain tetrahedral silicon and terminal hydrides. They only have Si−H and Si−Si single bonds. The bond lengths are 146.0 pm for a Si−H bond and 233 pm ...
In the context of group theory, the socle of a group G, denoted soc(G), is the subgroup generated by the minimal normal subgroups of G.It can happen that a group has no minimal non-trivial normal subgroup (that is, every non-trivial normal subgroup properly contains another such subgroup) and in that case the socle is defined to be the subgroup generated by the identity.