Phosphoryl group
A phosphoryl group is the chemical ion or radical: P+O32−, containing phosphorus and oxygen. (The correct chemical name for this −PO32− group is phosphonato, and phosphono for −PO3H2; as phosphoryl in chemical nomenclature means a trivalent > P(O)− group.) It may exist in different protonation states.
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The term is usually used to refer to compounds in which the phosphoryl group is attached to other atoms, e.g. phosphoryl chloride, or in the description of catalytic mechanisms (see: phosphorylation). In biochemical reactions involving phosphates (e.g. adenosine triphosphate), a phosphoryl group is usually transferred between the substrates (phosphoryl transfer reactions). A phosphoryl group should not be confused with a phosphate group.
The phosphoryl group plays the central role in phosphorylation.