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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 ...
Acid–base-catalysed hydrolyses are very common; one example is the hydrolysis of amides or esters. Their hydrolysis occurs when the nucleophile (a nucleus-seeking agent, e.g., water or hydroxyl ion) attacks the carbon of the carbonyl group of the ester or amide. In an aqueous base, hydroxyl ions are better nucleophiles than polar molecules ...
These reactions proceed via the intermediacy of amides. The intramolecular reaction of a carboxylic acid with an amide is far faster than the intermolecular reaction, which is rarely observed. They may also be produced via the oxidation of amides, particularly when starting from lactams. [6] R(CO)NHCH 2 R' + 2 [O] → R(CO)N(CO)R' + H 2 O
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 ...
IUPAC states "The esters are often called urethanes or urethans, a usage that is strictly correct only for the ethyl esters." [ 44 ] But also states, "An alternative term for the compounds R2NC(=O)OR' (R' not = H), esters of carbamic acids, R,NC(=O)OH, in strict use limited to the ethyl esters, but widely used in the general sense". [ 45 ]
An ester of a carboxylic acid.R stands for any group (typically hydrogen or organyl) and R ′ stands for any organyl group.. In chemistry, an ester is a compound derived from an acid (organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group (−OH) of that acid is replaced by an organyl group (R ′). [1]
The oxygen on the amide carbonyl group does not coordinate to the Zn 2+ until the addition of the water. The deprotonation of the Zn 2+ coordinated water by Glu 270 provides an activated hydroxide nucleophile which attacks the amide carbonyl group in the peptide bond in a nucleophilic addition.
Since water molecules attack amide-amide hydrogen bonds and break up secondary structure, a disulfide bond stabilizes secondary structure in its vicinity. For example, researchers have identified several pairs of peptides that are unstructured in isolation, but adopt stable secondary and tertiary structure upon formation of a disulfide bond ...