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The term phosphate is also used in organic chemistry for the functional groups that result when one or more of the hydrogens are replaced by bonds to other groups. These acids, together with their salts and esters , include some of the best-known compounds of phosphorus, of high importance in biochemistry , mineralogy , agriculture , pharmacy ...
The 5' end has a 5' carbon attached to a phosphate, and the other end, the 3' end, has a 3' carbon attached to a hydroxyl group. In chemistry, a phosphodiester bond occurs when exactly two of the hydroxyl groups (−OH) in phosphoric acid react with hydroxyl groups on other molecules to form two ester bonds.
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 ...
Acid phosphatase (EC 3.1.3.2, systematic name phosphate-monoester phosphohydrolase (acid optimum)) is an enzyme that frees attached phosphoryl groups from other molecules during digestion. It can be further classified as a phosphomonoesterase .
The pyrophosphate anion has the structure P 2 O 4− 7, and is an acid anhydride of phosphate. It is unstable in aqueous solution and hydrolyzes into inorganic phosphate: P 2 O 4− 7 + H 2 O → 2 HPO 2− 4. or in biologists' shorthand notation: PP i + H 2 O → 2 P i + 2 H +
Thus, below pH 5.5, phosphates add a single negative charge; near pH 6.5, they add 1.5 negative charges; above pH 7.5, they add 2 negative charges. The relative amount of each isoform can also easily and rapidly be determined from staining intensity on 2D gels.
It is a conjugate acid of phosphate [PO 4] 3-and a conjugate base of dihydrogen phosphate [H 2 PO 4] −. It is formed when a pyrophosphate anion [P 2 O 7] 4− reacts with water H 2 O by hydrolysis, which can give hydrogenphosphate: [P 2 O 7] 4− + H 2 O ⇌ 2 [HPO 4] 2−
[HP 2 O 7] 3− ⇌ [P 2 O 7] 4− + H +, pKa = 9.41. The pKa's occur in two distinct ranges because deprotonations occur on separate phosphate groups. For comparison with the pKa's for phosphoric acid are 2.14, 7.20, and 12.37. At physiological pH's, pyrophosphate exists as a mixture of doubly and singly protonated forms.