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Histidine ball and stick model spinning. 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 ...
An abnormally low pH in the extracellular fluid is called an acidemia and an abnormally high pH is called an alkalemia. [citation needed] Acidemia and alkalemia unambiguously refer to the actual change in the pH of the extracellular fluid (ECF). [24] Two other similar sounding terms are acidosis and alkalosis. They refer to the customary effect ...
The triad of cytomegalovirus protease [b] uses histidine as both the acid and base triad members. Removing the acid histidine results in only a 10-fold activity loss (compared to >10,000-fold when aspartate is removed from chymotrypsin). This triad has been interpreted as a possible way of generating a less active enzyme to control cleavage ...
Two-component systems accomplish signal transduction through the phosphorylation of a response regulator (RR) by a histidine kinase (HK). Histidine kinases are typically homodimeric transmembrane proteins containing a histidine phosphotransfer domain and an ATP binding domain, though there are reported examples of histidine kinases in the atypical HWE and HisKA2 families that are not ...
The use of acidosis for a low pH creates an ambiguity in its meaning. The difference is important where a patient has factors causing both acidosis and alkalosis, wherein the relative severity of both determines whether the result is a high, low, or normal pH. [citation needed] Alkalemia occurs at a pH over 7.45.
Histamine is derived from the decarboxylation of the amino acid histidine, a reaction catalyzed by the enzyme L-histidine decarboxylase. It is a hydrophilic vasoactive amine . Conversion of histidine to histamine by histidine decarboxylase
In computational biology, protein pK a calculations are used to estimate the pK a values of amino acids as they exist within proteins.These calculations complement the pK a values reported for amino acids in their free state, and are used frequently within the fields of molecular modeling, structural bioinformatics, and computational biology.
In cell biology, protein kinase A (PKA) is a family of serine-threonine kinase [1] whose activity is dependent on cellular levels of cyclic AMP (cAMP). PKA is also known as cAMP-dependent protein kinase (EC 2.7.11.11). PKA has several functions in the cell, including regulation of glycogen, sugar, and lipid metabolism.