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Arginine is the amino acid with the formula (H 2 N)(HN)CN(H)(CH 2) 3 CH(NH 2)CO 2 H. The molecule features a guanidino group appended to a standard amino acid framework. At physiological pH, the carboxylic acid is deprotonated (−CO 2 −) and both the amino and guanidino groups are protonated, resulting in a cation.
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 ...
Chemical formula: C 6 H 14 N 4 O 2 Molar mass: 174.2 g·mol −1 Systematic name: 2-amino-5-(diaminomethylidene amino)pentanoic acid Abbreviations: R, Arg Synonyms: 2-amino-5-guanidinopentanoic acid
pKa values for acetic, chloroacetic, dichloroacetic and trichloroacetic acids. Inductive effects and mesomeric effects affect the p K a values. A simple example is provided by the effect of replacing the hydrogen atoms in acetic acid by the more electronegative chlorine atom.
It appears that the pKa values in the arginine article might be in the wrong order. PubChem (Arginine, C6H14N4O2 - PubChem) lists arginine pKa values as pK1 = 2.18, pK2 = 9.09, and pK3 = 13.2. Mikestorm1 20:46, 14 April 2019 (UTC) Yes, only one pKa is listed, whereas the compound has 3 relevant values.
The following table presents pK a values at 20 °C. Values change by about 0.01 per degree of temperature. [1] [3] Good's original 1966 paper had two older buffers (marked with italics) for comparison. In 1972 Good published a second list with three more buffers, and five more were added in 1980.
Some improvements in the methodology (especially in the determination of the pK values for modified amino acids) have been also proposed. [ 8 ] [ 9 ] More advanced methods take into account the effect of adjacent amino acids ±3 residues away from a charged aspartic or glutamic acid , the effects on free C terminus, as well as they apply a ...
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.