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Chemical formula: C 6 H 9 N 3 O 2 Molar mass: 155.16 g·mol −1 Systematic name: 2-amino-3-(3H-imidazol-4-yl)propanoic acid Abbreviations: H, His Synonyms: Imidazole alanine ({S/D})-α-amino-1H-imidazole-4-propanoic acid
Histidine (symbol His or H) [2] is an essential amino acid that is used in the biosynthesis of proteins.It contains an α-amino group (which is in the protonated –NH 3 + form under biological conditions), a carboxylic acid group (which is in the deprotonated –COO − form under biological conditions), and an imidazole side chain (which is partially protonated), classifying it as a ...
Molar mass: 340.38 g/mol ... nitrogen from the imidazole side chain of the histidine, another nitrogen from the alpha-amino group of glycine and the deprotonated ...
Molar mass: 162.141 g·mol −1 Appearance ... Modification of histidine by DEPC results in carbethoxylated derivates at the N-omega-2 nitrogen of the imidazole ring.
Imidazole is the side chain of histidine and is typically used at a concentration of 150 - 500 mM for elution. Histidine or histamine can also be used. Decrease in pH; When the pH decreases, the histidine residue is protonated and can no longer coordinate the metal tag, allowing the protein to be eluted.
Imidazole is a planar 5-membered ring, that exists in two equivalent tautomeric forms because hydrogen can be bound to one or another nitrogen atom. Imidazole is a highly polar compound, as evidenced by its electric dipole moment of 3.67 D, [12] and is highly soluble in water.
The compound can be synthesized on a laboratory scale by methylation of imidazole at the pyridine-like nitrogen and subsequent deprotonation. [4] Similarly, 1-methylimidazole may be synthesized by first deprotonating imidazole to form a sodium salt followed by methylation. [5] [6] H 2 C 2 N(NH)CH + CH 3 I → [H 2 C 2 (NH)(NCH 3)CH]I
For example, mammalian and tuna cytochrome c contain a single heme C that is axially coordinated to side chains of both histidine and methionine. [8] Perhaps because of the two covalent bonds holding the heme to the protein, the iron of heme C is sometimes axially ligated to the amino group of lysine or even water.