Peptide: Difference between revisions
Eran Hodis (talk | contribs) No edit summary |
Eran Hodis (talk | contribs) No edit summary |
||
| Line 2: | Line 2: | ||
Peptides are chains of amino acids linked by peptide bonds. Long peptides, or polypeptides, are called proteins. | Peptides are chains of amino acids linked by peptide bonds. Long peptides, or polypeptides, are called proteins. | ||
<jmol> | |||
<jmolCheckbox> | |||
<scriptWhenChecked>spin on</scriptWhenChecked> | |||
<scriptWhenUnchecked>spin off</scriptWhenUnchecked> | |||
<text>Spin</text> | |||
</jmolCheckbox> | |||
</jmol> | |||
==Peptides & Backbones== | ==Peptides & Backbones== | ||
This is the <scene name='Peptide/Emartz_view1/6'>backbone</scene> of 1 amino acid. Adding to the backbone with an additional amino acid on each side gives a <scene name='Peptide/Emartz_view2/6'>tripeptide</scene> (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 <scene name='Peptide/Emartz_view3/4'>Ala-Ala-Ala</scene> (tri-alanine). Adding a carbon chain plus an NH3 on the first amino acid gives <scene name='Peptide/Emartz_view4/5'>Lys-Ala-Ala</scene>. Adding <scene name='Peptide/Emartz_view5/4'>three more carbons</scene> to the 3rd amino acid gives [[isoleucine]]: Lys-Ala-Ile. The 4th amino acid is threonine with its hydroxyl, giving <scene name='Peptide/Emartz_view6/2'>Lys-Ala-Ile-Thr</scene>. Here is the shape of the <scene name='Peptide/Emartz_view7/2'>tetrapeptide</scene> (4 AAs). The stick representation has too much detail for larger proteins, so the α-carbons are connected with a line called the <scene name='Peptide/Emartz_view8/3'>backbone trace</scene>. Showing only the <scene name='Peptide/Emartz_view9/5'>backbone</scene> makes it easier to see the path of the protein chain (its secondary and tertiary structure). | This is the <scene name='Peptide/Emartz_view1/6'>backbone</scene> of 1 amino acid. Adding to the backbone with an additional amino acid on each side gives a <scene name='Peptide/Emartz_view2/6'>tripeptide</scene> (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 <scene name='Peptide/Emartz_view3/4'>Ala-Ala-Ala</scene> (tri-alanine). Adding a carbon chain plus an NH3 on the first amino acid gives <scene name='Peptide/Emartz_view4/5'>Lys-Ala-Ala</scene>. Adding <scene name='Peptide/Emartz_view5/4'>three more carbons</scene> to the 3rd amino acid gives [[isoleucine]]: Lys-Ala-Ile. The 4th amino acid is threonine with its hydroxyl, giving <scene name='Peptide/Emartz_view6/2'>Lys-Ala-Ile-Thr</scene>. Here is the shape of the <scene name='Peptide/Emartz_view7/2'>tetrapeptide</scene> (4 AAs). The stick representation has too much detail for larger proteins, so the α-carbons are connected with a line called the <scene name='Peptide/Emartz_view8/3'>backbone trace</scene>. Showing only the <scene name='Peptide/Emartz_view9/5'>backbone</scene> makes it easier to see the path of the protein chain (its secondary and tertiary structure). | ||