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Peptide bond formation via dehydration reaction. When two amino acids form a dipeptide through a peptide bond, [1] it is a type of condensation reaction. [2] In this kind of condensation, two amino acids approach each other, with the non-side chain (C1) carboxylic acid moiety of one coming near the non-side chain (N2) amino moiety of the other.
A new development for producing longer peptide chains is chemical ligation: unprotected peptide chains react chemoselectively in aqueous solution. A first kinetically controlled product rearranges to form the amide bond. The most common form of native chemical ligation uses a peptide thioester that reacts with a terminal cysteine residue. [58]
Peptides are short chains of amino acids linked by peptide bonds. [ 1 ] [ 2 ] A polypeptide is a longer, continuous, unbranched peptide chain. [ 3 ] Polypeptides that have a molecular mass of 10,000 Da or more are called proteins . [ 4 ]
The peptidyl transferase center (EC 2.3.2.12) is an aminoacyltransferase ribozyme (RNA enzyme) located in the large subunit of the ribosome.It forms peptide bonds between adjacent amino acids during the translation process of protein biosynthesis. [1]
This class of reactions is a vital part of life as it is essential to the formation of peptide bonds between amino acids and to the biosynthesis of fatty acids. [4] Idealized scheme showing condensation of two amino acids to give a peptide bond. Many variations of condensation reactions exist.
A peptide bond forms between the amino acid attached to the tRNA in the P site and the amino acid attached to a tRNA in the A site. The formation of a peptide bond requires an input of energy. The two reacting molecules are the alpha amino group of one amino acid and the alpha carboxyl group of the other amino acids.
Turns are classified [2] according to the separation between the two end residues: In an α-turn the end residues are separated by four peptide bonds (i → i ± 4). In a β-turn (the most common form), by three bonds (i → i ± 3). In a γ-turn, by two bonds (i → i ± 2). In a δ-turn, by one bond (i → i ± 1), which is sterically unlikely.
However, additional molecular interactions may render the amide form less stable; the amino group is expelled instead, resulting in an ester (Ser/Thr) or thioester (Cys) bond in place of the peptide bond. This chemical reaction is called an N-O acyl shift. The ester/thioester bond can be resolved in several ways: