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pKa values for acetic, chloroacetic, dichloroacetic and trichloroacetic acids. Inductive effects and mesomeric effects affect the pK a values. A simple example is provided by the effect of replacing the hydrogen atoms in acetic acid by the more electronegative chlorine atom.
pK a values of amino acid side chains play an important role in defining the pH-dependent characteristics of a protein. The pH-dependence of the activity displayed by enzymes and the pH-dependence of protein stability, for example, are properties that are determined by the pK a values of amino acid side chains.
Citric acid is a triprotic acid, with pK a values, extrapolated to zero ionic strength, of 3.128, 4.761, and 6.396 at 25 °C. [21] The pK a of the hydroxyl group has been found, by means of 13 C NMR spectroscopy, to be 14.4. [22] The speciation diagram shows that solutions of citric acid are buffer solutions between about pH 2 and pH 8. In ...
The difference between successive pK a values is sufficiently large so that salts of either monohydrogen phosphate, HPO 2− 4 or dihydrogen phosphate, H 2 PO − 4, can be prepared from a solution of phosphoric acid by adjusting the pH to be mid-way between the respective pK a values.
In chemistry, biochemistry, and pharmacology, a dissociation constant (K D) is a specific type of equilibrium constant that measures the propensity of a larger object to separate (dissociate) reversibly into smaller components, as when a complex falls apart into its component molecules, or when a salt splits up into its component ions.
Oxalic acid's pK a values vary in the literature from 1.25 to 1.46 and from 3.81 to 4.40. [ 26 ] [ 27 ] [ 28 ] The 100th ed of the CRC, released in 2019, has values of 1.25 and 3.81. [ 29 ] Oxalic acid is relatively strong compared to other carboxylic acids :
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.
At pH 1 or lower, the phosphoric acid is practically undissociated. Around pH 4.7 (mid-way between the first two pK a values) the dihydrogen phosphate ion, [H 2 PO 4] −, is practically the only species present. Around pH 9.8 (mid-way between the second and third pK a values) the monohydrogen phosphate ion, [HPO 4] 2−, is the only species ...