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[4] [5] The amide group is called a peptide bond when it is part of the main chain of a protein, and an isopeptide bond when it occurs in a side chain, as in asparagine and glutamine. It can be viewed as a derivative of a carboxylic acid ( R−C(=O)−OH ) with the hydroxyl group ( −OH ) replaced by an amine group ( −NR′R″ ); or ...
Like lidocaine, bupivacaine is an amino-amide anesthetic; the aromatic head and the hydrocarbon chain are linked by an amide bond rather than an ester as in earlier local anesthetics. As a result, the amino-amide anesthetics are more stable and less likely to cause allergic reactions.
Structurally, amino esters consist of three molecular components: a lipophilic part (ester); an intermediate aliphatic chain; a hydrophilic part (amine); The chemical linkage between the lipophilic part and the intermediate chain can be of the amide-type or the ester-type, and is the general basis for the current classification of local anesthetics.
Example of a depsipeptide with 3 amide groups (highlighted blue) and one ester group (highlighted green). R 1 and R 3 are organic groups (e. g. methyl) or a hydrogen atom found in α-hydroxycarboxylic acids. R 2, R 4 and R 5 are organic groups or a hydrogen atom found in common amino acids.
Amide Polar Neutral −3.5 132.119 3.93 AAY Aspartate: Asp D Anion Brønsted base: Negative −3.5 133.104 5.49 GAY Cysteine: Cys C Thiol Brønsted acid Neutral 2.5 250 0.3 121.154 1.38 UGY Glutamine: Gln Q Amide Polar Neutral −3.5 146.146 3.9 CAR Glutamate: Glu E Anion Brønsted base Negative −3.5 147.131 6.32 GAR Glycine: Gly G Aliphatic ...
The two major resonance forms of an amide. Another factor that plays a role in determining the reactivity of acyl compounds is resonance. Amides exhibit two main resonance forms. Both are major contributors to the overall structure, so much so that the amide bond between the carbonyl carbon and the amide nitrogen has significant double bond ...
Ether phospholipids: phospholipids are known to have ether-linked "tails" instead of the usual ester linkage. [1] Ether on sn-1, ester on sn-2: "ether lipids" in the context of bacteria and eukaryotes refer to this class of lipids. Compared to the usual 1,2-diacyl-sn-glycerol (DAG), the sn-1 linkage is replaced with an ester bond. [1] [2] [3]
The difference in pK a can be quantified to reflect the salt bridge’s contribution to free energy. Using Gibbs free energy : Δ G = − RT ln( K eq ), where R is the universal gas constant, T is the temperature in kelvins, and K eq is the equilibrium constant of a reaction in equilibrium.