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Peptide bond. In organic chemistry, a peptide bond is an amide type of covalent chemical bond linking two consecutive alpha-amino acids from C1 (carbon number one) of one alpha-amino acid and N2 (nitrogen number two) of another, along a peptide or protein chain.
Drosomycin, an example of a peptide. 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]
In organic chemistry, peptide synthesis is the production of peptides, compounds where multiple amino acids are linked via amide bonds, also known as peptide bonds. Peptides are chemically synthesized by the condensation reaction of the carboxyl group of one amino acid to the amino group of another.
[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 ...
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:
Chemical structure of the peptide bond (bottom) and the three-dimensional structure of a peptide bond between an alanine and an adjacent amino acid (top/inset). The bond itself is made of the CHON elements. Resonance structures of the peptide bond that links individual amino acids to form a protein polymer
Chemical ligation of unprotected peptides is enabled by formation of an unnatural moiety, i.e. non-peptide bond, linking the two peptide segments in the ligation product. It was envisioned as a general method that would greatly simplify the chemical synthesis of protein molecules and enable the application of the entire repertoire of chemistry ...
According to one definition, a turn is a structural motif where the C α atoms of two residues separated by a few (usually 1 to 5) peptide bonds are close (less than 7 Å [0.70 nm]). [1] The proximity of the terminal C α atoms often correlates with formation of an inter main chain hydrogen bond between the corresponding residues. Such hydrogen ...