Organophosphate
Organophosphates (also known as phosphate esters) are a class of organophosphorus compounds with the general structure O=P(OR). They can be considered as esters of phosphoric acid. Like most functional groups organophosphates occur in a diverse range of forms, with important examples including key biomolecules such as DNA, RNA and ATP, as well as many insecticides, herbicides, and nerve agents.
Exopolyphosphatase
PPX was discovered by the lab of Nobel laureate Arthur Kornberg in 1993 and is part of the polyphosphate operon along with polyphosphate kinase, the enzyme which synthesizes polyphosphate. The Kornberg lab was very interested in polyphosphate and published a series of papers elucidating the metabolism and roles of polyphosphate "in vivo". Their interest in polyphosphate led them to identify and characterize the polyphosphate operon (which includes polyphosphate kinase [PPK] and PPX) and develop a wide variety of assays and techniques for quantification of polyphosphate production and degradation, "in vitro" and "in vivo". The results of these studies of polyphosphate by the Kornberg lab led Kornberg to speculate that due to its high energy and phosphate content and the degree to which it is conserved across species, polyphosphate may have been the precursor to RNA, DNA, and proteins.