Amino acid residue: Difference between revisions

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When two or more [[amino acids|amino acids]] combine to form a [[peptide|peptide]], the elements of [[water|water]] are removed, and what remains of each amino acid is called an amino-acid residue. α-Amino-acid residues are therefore structures that lack a [[hydrogen|hydrogen]] [[atom|atom]] of the [[amino group|amino group]] (–NH–CHR–COOH), or the [[hydroxyl |hydroxyl ]]moiety of the [[carboxyl group|carboxyl group]] (NH<sub>2</sub>–CHR–CO–), or both (–NH–CHR–COO–); all units of a peptide chain are therefore amino-acid residues. (Residues of amino acids that contain two amino groups or two carboxyl groups may be joined by [[isopeptide bond|isopeptide bonds]], and so may not have the formulas shown.) The residue in a peptide that has an amino group that is free, or at least not acylated by another amino-acid residue (it may, for example, be acylated or formylated), is called [[N-terminal|N-terminal]]; it is at the N-terminus. The residue that has a free carboxyl group, or at least does not acylate another amino-acid residue, (it may, for example, acylate ammonia to give –NH–CHR–CO–NH<sub>2</sub>), is called [[C_terminal|C-terminal]]<ref>IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997). XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8. https://doi.org/10.1351/goldbook.</ref>.<sup></sup>  
When two or more [[Amino acids|amino acids]] combine to form a [[Peptide|peptide]], the elements of [[Water|water]] are removed, and what remains of each amino acid is called an amino-acid residue. It is basically an amino acid once inside the [https://teaching.ncl.ac.uk/bms/wiki/index.php/Polypeptide polypeptide] chain, which means it is an amino acid but with its alpha-[https://teaching.ncl.ac.uk/bms/wiki/index.php/Amino_group amino] and[https://teaching.ncl.ac.uk/bms/wiki/index.php/Carboxyl carboxyl ]group as part of the peptide bonds. (Residues of amino acids that contain two amino groups or two carboxyl groups may be joined by [[Isopeptide bond|isopeptide bonds]], and so may not have the formulas shown.)<ref />


=== References  ===
=== References  ===


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Revision as of 01:51, 23 November 2018

When two or more amino acids combine to form a peptide, the elements of water are removed, and what remains of each amino acid is called an amino-acid residue. It is basically an amino acid once inside the polypeptide chain, which means it is an amino acid but with its alpha-amino andcarboxyl group as part of the peptide bonds. (Residues of amino acids that contain two amino groups or two carboxyl groups may be joined by isopeptide bonds, and so may not have the formulas shown.)Cite error: The opening <ref> tag is malformed or has a bad name

References

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