Peptide
From Proteopedia
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<applet load="pepb27_4.pdb" size="300" color="white" frame="true" caption="Peptides are small chains of amino acids." align="right" /> | <applet load="pepb27_4.pdb" size="300" color="white" frame="true" caption="Peptides are small chains of amino acids." align="right" /> | ||
| - | + | Peptides are chains of amino acids linked by peptide bonds. Long peptides, or polypeptides, are called proteins. | |
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| + | ==Peptides & Backbones== | ||
| + | This is the backbone of 1 amino acid. Adding to the backbone with an additional amino acid on each side gives a tripeptide (3 amino acids). No side groups are shown, and most hydrogens are omitted. Now each amino acid has a 1 carbon side group so we have Ala-Ala-Ala (tri-alanine). Adding a carbon chain plus an NH3 on the first amino acid gives Lys-Ala-Ala. Adding three more carbons to the 3rd amino acid gives [[isoleucine]]: Lys-Ala-Ile. The 4th amino acid is threonine with its hydroxyl, giving Lys-Ala-Ile-Thr. Here is the shape of the tetrapeptide (4 AAs). The stick representation has too much detail for larger proteins, so the α-carbons are connected with a line called the backbone trace. Showing only the backbone makes it easier to see the path of the protein chain (its secondary and tertiary structure). | ||
Revision as of 08:58, 11 October 2007
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Peptides are chains of amino acids linked by peptide bonds. Long peptides, or polypeptides, are called proteins.
Peptides & Backbones
This is the backbone of 1 amino acid. Adding to the backbone with an additional amino acid on each side gives a tripeptide (3 amino acids). No side groups are shown, and most hydrogens are omitted. Now each amino acid has a 1 carbon side group so we have Ala-Ala-Ala (tri-alanine). Adding a carbon chain plus an NH3 on the first amino acid gives Lys-Ala-Ala. Adding three more carbons to the 3rd amino acid gives isoleucine: Lys-Ala-Ile. The 4th amino acid is threonine with its hydroxyl, giving Lys-Ala-Ile-Thr. Here is the shape of the tetrapeptide (4 AAs). The stick representation has too much detail for larger proteins, so the α-carbons are connected with a line called the backbone trace. Showing only the backbone makes it easier to see the path of the protein chain (its secondary and tertiary structure).
