Concentration of inorganic phosphate (Pi)

Value ~50 mM
Organism Budding yeast Saccharomyces cerevisiae
Reference Orij R, Brul S, Smits GJ. Intracellular pH is a tightly controlled signal in yeast. Biochim Biophys Acta. 2011 Oct1810(10):933-44. doi: 10.1016/j.bbagen.2011.03.011. p.933 left columnPubMed ID21421024
Primary Source van Eunen K. et al., Measuring enzyme activities under standardized in vivo-like conditions for systems biology. FEBS J. 2010 Feb277(3):749-60PubMed ID20067525
Comments "The pH of a solution is defined as the negative logarithm of the hydrogen ion activity in water. If [investigators] assume the inside of a yeast cell to be a watery solution, [they] can estimate the number of free protons in the cytosol of a single cell (48 µm^3 [refs 1,2] at a pH of 7 [ref 3]) at no more than ~3000. In contrast, global analysis of protein expression in yeast tells us that the number of protein molecules in a cell is in the order of millions [ref 4]. Each of these proteins has multiple protonatable groups which can either donate or take up a proton. In addition, acidic metabolites are also in excess compared to free protons. For instance, the concentration of inorganic phosphate (Pi) in yeast cells is estimated at around 50 mM [primary source], five orders of magnitude higher than that of protons. This difference in the numbers of free protons and potential buffer molecules is important for [investigators’] perception of pHi." See BNID 106019
Entered by Uri M
ID 106511