200 - 300 g/Liter
||Bacteria Escherichia coli
||Mika JT, Schavemaker PE, Krasnikov V, Poolman B. Impact of osmotic stress on protein diffusion in Lactococcus lactis. Mol Microbiol. 2014 Nov94(4):857-70. doi: 10.1111/mmi.12800. p.857 right column top paragraphPubMed ID25244659
||Konopka, M.C., Weisshaar, J.C., and Record, M.T., Jr (2007) Methods of changing biopolymer volume fraction and cytoplasmic solute concentrations for in vivo biophysical studies. Methods Enzymol. 428: 487–504.PubMed ID17875435
||P.857 right column top paragraph:"The cellular milieu is far different from idealized test tube conditions (Ellis, 2001 Gierasch and Gershenson, 2009), with much higher macromolecule concentrations, more interaction partners, a spatially heterogenous and often a compartmentalized nature. One of the major differences between in vivo and in vitro conditions is the crowdedness (and associated molecular complexity) of the cytoplasm and biological membranes (Gershenson and Gierasch, 2011). Protein diffusion in this environment is significantly slower than in dilute solutions or idealized in vitro systems. For example the diffusion of GFP in water, with a diffusion coefficient (D) of ∼ 90 μm^2 s^−1 (BNID 100301), is faster than in the cytoplasm of eukaryotic cells (D = 24–27 μm^2 s^−1) (BNID 112266) or prokaryotic cells (D = 3–14 μm^2 s^−1) (BNID 112266). This difference is often rationalized by the elevated macromolecule crowding of living cells with values reaching on average 200–300 g l^−1 of macromolecules in the cytoplasm of Escherichia coli (primary source)."