Phosphorus in proteins

Detection of Nitrogen, Sulphur, and Phosphorus in Proteins.—The methods described below illustrate those commonly used in the analysis of proteins. 

The results obtained by the author and described in this review represent the first experimental demonstration of the existence of diester and pyrophosphate bonds in proteins. Moreover, they add a new type of crosslinks to that of the disulfide bonds. As in the case of the sulfur bridges, the phosphorus in proteins either can link different peptide chains, as in a- and /3-casein, or may serve to connect two sites of a single chain in a cyclic loop as in pepsin. 

The central role of cyclic nucleotides in regulating a wide range of important biological functions requires examination of the mechanisms of their enzymic synthesis and breakdown. Above all, their biological importance demands a response to the question What design feature of cyclic nucleotides makes these molecules ideal as intracellular messengers In the light of the subject of this review, we must add the rider Is there a role for nucleophilic substitution at phosphorus in protein kinase activation ... 

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