| Atom Label | Description |
| C | Main chain Carbon of amide/acid |
| CA | Main chain α carbon |
| N | Main chain nitrogen of amide/amine |
| O | Main chain Oxygen of amide/acid |
| H | Main chain hydrogen of amide |
| HA | Main chain hydrogen of on the α carbon |
| CB | β Carbon, first carbon of the sidechain |
| HB? | Hydrogen on the β Carbon. '?' is a number 1,2 or 3 |
| OG | Oxygen on the β Carbon. |
| CG? | γ Carbon. - the '?' if present is a number 1 or 2 |
The results are shown. The H from the -OH group on C6 is now on the amino acid side chain. The phosphate group has been transferred to the alcohol carbon of glucose and ADP is the other product.
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| Name | 3 Letter | 1 Letter | Histidine | HIS | H | |
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| Drawn as if part of protein to emphasize the sidechain properties | The "Sidechain Polarity" button draws an an envelope around the sidechain that is colored by charge according to the scale above. The envelope shown here is only for the unprotonated - neutral form of the sidechain. |
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| pKR in H2O= 6.5 | Free amino acid Mass = 155 g/M | |||||
| Probability of being found in a: | ||||||
| α-Helix | β-Sheet | β-Turn | ||||
| 60% | 60% | 60% | ||||
| Special Attributes | ||||||
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This amino acid has a cyclic group called an Imidazole group which has a pK right in the physiological pH range. Therefore its protonation state varies widely depending on the situation and the environment. In the demonstration below, the histidine is in a short piece of α-helix and the sidechain is exposed to solvent. |
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| Jmol: an open-source Java viewer for chemical structures in 3D. http://www.jmol.org/ | ||||||