Regulation of intracellular pyrophosphatase-activity and conservation of the phosphoanhydride-energy of inorganic pyrophosphate in microbial metabolism.

The conservation of the phosphoanhydride-energy of inorganic pyrophosphate (PP) in microbial metabolism requires a stringent metabolic control of the intracellular pyrophosphatases (PPases, EC 3.6.1.1). In this article, the rate of intracellular PP-liberation during biosynthesis of cellular constituents is calculated from the specific growth rate and the macromolecular composition of the respective microorganism. This rate is compared with the maximal specific activity of PPase in cell free extracts or purified enzyme preparations in order to investigate the possibility of the limitation of biosynthesis through PPase-activity. The catalytic and regulatory properties of microbial PPases are discussed in respect to the occurrence of PP-dependent ransphosphorylases. The evidence showing that certain anaerobic microorganisms including photosynthetic bacteria, can use PP instead of ATP as phosphate donor for transphosphorylation reactions will be discussed.