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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 ...
^a CID 71083 from PubChem (D-histidine) ^a CID 6274 from PubChem (L-histidine) This page was last edited on 12 April 2023, at 11:40 (UTC). Text is available under ...
Acetonitrile is less basic than DMSO, and, so, in general, acids are weaker and bases are stronger in this solvent. Some pK a values at 25 °C for acetonitrile (ACN) [37] [38] [39] and dimethyl sulfoxide (DMSO). [40] are shown in the following tables. Values for water are included for comparison.
See Amino acid for the pK a values of all amino acid side chains inferred in such a way. There are also numerous experimental studies that have yielded such values, for example by use of NMR spectroscopy. The table below lists the model pK a values that are often used in a protein pK a calculation, and contains a third column based on protein ...
The endothelial protease vasohibin [f] uses a cysteine as the nucleophile, but a serine to coordinate the histidine base. [43] [44] Despite the serine being a poor acid, it is still effective in orienting the histidine in the catalytic triad. [43] Some homologues alternatively have a threonine instead of serine at the acid location. [43]
The value for Arg is from Pace et al. (2009). [7] The value for Sec is from Byun & Kang (2011). [8] N.D.: The pKa value of Pyrrolysine has not been reported. Note: The pKa value of an amino-acid residue in a small peptide is typically slightly different when it is inside a protein.
Sinkholes occur in the area because of subsidence from coal mining activity. Rescuers had been using water to break down and remove clay and dirt from the mine, which has been closed since the 1950s.
Like EDTA, its sodium salt is used for water softening to remove Ca 2+. For this purpose, NTA is a replacement for triphosphate, which once was widely used in detergents, and cleansers, but can cause eutrophication of lakes. In one application, sodium NTA removes Cr, Cu, and As from wood that had been treated with chromated copper arsenate. [9]