Phosphoryl and Sulfuryl Transfer

Biochemical reactions of phosphate and sulfate esters are ubiquitous in the living world, and are found throughout many pathways involving metabolism, biosynthesis, control of transcription, energy storage, and replication. This chapter describes the mechanisms by which phosphate and sulfate monoesters undergo uncatalyzed and enzyme-catalyzed hydrolysis by phosphatases and sulfatases, respectively. Relative to the slow rates of the uncatalyzed reactions of their substrates, these enzymes produce rate accelerations that are among the greatest of any enzymes yet described. Interestingly, nature has evolved several quite different catalytic strategies to accomplish this. This review summarizes the current state of knowledge of several phosphatases and sulfatases. Phosphatases and sulfatases constitute a large group of enzymes, with structural and mechanistic diverseness. Within each group, one finds enzymes that utilize completely different catalytic machinery and mechanisms to accomplish the same reaction. We also summarize the mechanistic tools that have been used to study the chemistry and biochemistry of sulfate and phosphate esters, with references to comprehensive treatments of these methods for those who wish more thorough explanations of the tools of enzymology and physical organic chemistry.