Amino Acids
From Proteopedia
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The list below will gradually be expanded to include all 20 amino acids. | The list below will gradually be expanded to include all 20 amino acids. | ||
| - | ===Histidine | + | ===Histidine=== |
| + | His H: | ||
Charged: <font color="blue"><b>Basic</b></font>, Aromatic, Bulky | Charged: <font color="blue"><b>Basic</b></font>, Aromatic, Bulky | ||
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The sidechain of His can be positively charged (protonated), in which case both of the nitrogens in the sidechain imidazole ring have hydrogens, and the charge is delocalized between them. The pKa for protonation is 6.1. This means that, on average at any moment, half of the His sidechains are protonated when the pH is 6.1. At the pH of blood, 7.4 ±0.05, more than 90% of the His sidechains are positively charged. | The sidechain of His can be positively charged (protonated), in which case both of the nitrogens in the sidechain imidazole ring have hydrogens, and the charge is delocalized between them. The pKa for protonation is 6.1. This means that, on average at any moment, half of the His sidechains are protonated when the pH is 6.1. At the pH of blood, 7.4 ±0.05, more than 90% of the His sidechains are positively charged. | ||
| - | ===Tryptophan | + | ===Tryptophan=== |
| + | Trp W: | ||
Neutral, Polar, Aromatic, Bulky | Neutral, Polar, Aromatic, Bulky | ||
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In trans-membrane proteins, tryptophans often lie at the interface between water and lipid. An example is the potassium channel, e.g. [[1bl8]]. To see their positions, use the ''Find'' dialog in FirstGlance in Jmol. | In trans-membrane proteins, tryptophans often lie at the interface between water and lipid. An example is the potassium channel, e.g. [[1bl8]]. To see their positions, use the ''Find'' dialog in FirstGlance in Jmol. | ||
| - | ===Tyrosine | + | ===Tyrosine=== |
| + | Tyr Y: | ||
Neutral, Polar, Aromatic, Bulky | Neutral, Polar, Aromatic, Bulky | ||
Revision as of 13:40, 23 May 2009
For a general introduction to amino acids, please see Amino Acids in Wikipedia.
Contents |
20 Standard Amino Acids and Mnemonics
Here are the names of the twenty standard amino acids, with their three and one-letter abbreviations. Mnemonic names are intended to help you to remember the one-letter codes, but are not the correct names.
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Ala A Alanine
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Gln Q Glutamine |
Leu L Leucine
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Ser S Serine
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Structure, Properties, Behaviors in Proteins
Angel Herráez has provided a tutorial introduction to amino acid structure in which each of the 20 amino acids may be visualized in 3D using Jmol.
The list below will gradually be expanded to include all 20 amino acids.
Histidine
His H: Charged: Basic, Aromatic, Bulky
See Histidine in Wikipedia, where the structure is shown. The sidechain of His can be positively charged (protonated), in which case both of the nitrogens in the sidechain imidazole ring have hydrogens, and the charge is delocalized between them. The pKa for protonation is 6.1. This means that, on average at any moment, half of the His sidechains are protonated when the pH is 6.1. At the pH of blood, 7.4 ±0.05, more than 90% of the His sidechains are positively charged.
Tryptophan
Trp W: Neutral, Polar, Aromatic, Bulky
See Tryptophan in Wikipedia, where the structure is shown. In trans-membrane proteins, tryptophans often lie at the interface between water and lipid. An example is the potassium channel, e.g. 1bl8. To see their positions, use the Find dialog in FirstGlance in Jmol.
Tyrosine
Tyr Y: Neutral, Polar, Aromatic, Bulky
See Tyrosine in Wikipedia, where the structure is shown.
