Information AboutHistidine |
| CATEGORIES ABOUT HISTIDINE | |
| proteinogenic amino acids | |
| basic amino acids | |
| essential amino acids | |
| imidazoles | |
Histidine is one of the 20 most common natural to the aromatic ring and as such is slighty Acidic , whereas the other one donates only one electron to the ring so it has a free lone pair and is Basic . These properties are exploited in different ways in proteins. In Catalytic Triad s, the basic nitrogen of histidine is used to abstract a proton from Serine , Threonine or Cysteine to activate it as a Nucleophile . In a histidine proton shuttle, histidine is used to quickly shuttle protons, it can do this by abstracting a proton with its basic nitrogen to make a positively-charged intermediate and then use another molecule, a buffer, to extract the proton from its acidic nitrogen. In Carbonic Anhydrase s, a histidine proton shuttle is utilized to rapidly shuttle protons away from a zinc-bound water molecule to quickly regenerate the active form of the enzyme. The amino acid is a precursor for Histamine and Carnosine biosynthesis. There are two Isoforms : D-histidine and L-histidine. REFERENCES |
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