The biological importance of organophosphorus compounds containing a carbon-phosphorus bond.

Organophosphorus anticholinesterase compounds may be derivatives of phosphoric acid or of a phosphonic acid. The phosphonic acid derivatives are usually more reactive and more toxic than the phosphoric acid derivatives. Examples are given to show that differences in the chemical and biological reactivity of phosphates and phosphonates reflect many different aspects of their chemical structure. Some recently discovered naturally-occurring phosphonates are described, together with some synthetic phosphonate analogues of naturally-occurring phosphates. The utility of these synthetic phosphonates as tools for probing enzymic reaction sequences is discussed.