Basics of Protein Structure: Difference between revisions
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== Levels of Protein Structure == | == Levels of Protein Structure == | ||
There are [[Four levels of protein structure|four different levels of protein structure]]. The <scene name='60/604417/Ins_bead_backbone_labels/1'>primary structure</scene> is the amino acid sequence. The amino acids are connected by an amide bond, made from the amino group (NH2) of one amino acid, and the carboxylic acid (C=O) from another amino acid. The amino acids are linked in a repeating pattern. The [[Backbone representations|backbone]] of the protein is the repeating N-C-C=O pattern, with the side chains projecting out from the backbone. The end with the free -NH2 group is called the Amino or N terminus, while the end with a free carboxylic acid is called the C terminus. The sequence of amino acids is written and numbered from the N terminus (where protein synthesis begins) to the C terminus (where amino acids are added during protein synthesis). | There are [[Four levels of protein structure|four different levels of protein structure]]. The <scene name='60/604417/Ins_bead_backbone_labels/1'>primary structure</scene> is the amino acid sequence. The amino acids are connected by an amide bond, made from the amino group (NH2) of one amino acid, and the carboxylic acid (C=O) from another amino acid. The amino acids are linked in a repeating pattern. The [[Backbone representations|backbone]] of the protein is the repeating N-C-C=O pattern, with the side chains projecting out from the backbone. The end with the free -NH2 group is called the Amino or <scene name='60/604417/N_terminus/1'>N terminus</scene>, while the end with a free carboxylic acid is called the <scene name='60/604417/C_terminus/1'>C terminus</scene>. The sequence of amino acids is written and numbered from the N terminus (where protein synthesis begins) to the C terminus (where amino acids are added during protein synthesis), so for <scene name='60/604417/N_to_c/1'>the segment shown</scene>, the sequence would be Val-Asn-Gln. For more practice identifying peptide bonds between amino acids, please try [[User:Stephen Mills/Peptide tutorial 1|Peptide tutorial 1 part 1]] and [[User:Stephen Mills/Peptide tutorial 2|Peptide tutorial 1 part 2]]. | ||
The second level of structure is called secondary structure, and is the shapes (conformations) formed by short sequences of amino acids. This level of structure is stabilized by <scene name='57/575866/H_bond_a_helix/3'>hydrogen bonds</scene> along the <scene name='57/575866/Backbone/2'>backbone</scene>. (More about [[hydrogen bonds]].) The two most common shapes are [[Helices in Proteins|alpha helices]] and [[Sheets in Proteins|beta strands]]. These are favored simply because [[Tutorial:Ramachandran principle and phi psi angles|two atoms cannot occupy the same space]] (steric collisions). | The second level of structure is called secondary structure, and is the shapes (conformations) formed by short sequences of amino acids. This level of structure is stabilized by <scene name='57/575866/H_bond_a_helix/3'>hydrogen bonds</scene> along the <scene name='57/575866/Backbone/2'>backbone</scene>. (More about [[hydrogen bonds]].) The two most common shapes are [[Helices in Proteins|alpha helices]] and [[Sheets in Proteins|beta strands]]. These are favored simply because [[Tutorial:Ramachandran principle and phi psi angles|two atoms cannot occupy the same space]] (steric collisions). | ||
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** [[Amino Acids]] | ** [[Amino Acids]] | ||
** [[Peptide]] | ** [[Peptide]] | ||
** [[Phi and Psi Angles]] | ** [[Phi and Psi Angles]] | ||
** [[Ramachandran Plots]] | ** [[Ramachandran Plots]] | ||