Diffusion coefficients

Range fluorescently labeled glucose 50: GFP 3: 4×GFP-tagged β-galactosidase 0.8: 25–50 MDa ribosome-loaded mRNAs 0.02 µm^2/sec
Organism Bacteria Escherichia coli
Reference Theillet FX et al., Physicochemical properties of cells and their effects on intrinsically disordered proteins (IDPs). Chem Rev. 2014 Jul 9 114(13):6661-714. doi: 10.1021/cr400695p p.6669 right column top paragraphPubMed ID24901537
Primary Source [164] Mika JT, Poolman B. Macromolecule diffusion and confinement in prokaryotic cells. Curr Opin Biotechnol. 2011 Feb22(1):117-26. doi: 10.1016/j.copbio.2010.09.009PubMed ID20952181
Method Primary source abstract: "[Investigators] review recent observations on the mobility of macromolecules and their spatial organization in live bacterial cells. [They] outline the major fluorescence microscopy-based methods to determine the mobility and thus the diffusion coefficients (D) of molecules, which is not trivial in small cells…. Building on in vitro experiments and modeling studies, [they] evaluate the size dependence of diffusion coefficients for macromolecules in vivo, in case of both water-soluble and integral membrane proteins."
Comments P.6669 left column bottom paragraph: "What are the biological consequences of slowed intracellular diffusion? Although the crowded cytoplasm of prokaryotic and eukaryotic cells restricts translational diffusion, most biological reactions occur faster than diffusion. Mika et al. calculated that inside E. coli (∼3 μm long) it takes 30 ms for fluorescently labeled glucose (MW ∼0.3 kDa, D = 50 μm^2/s), 0.5 s for GFP (MW ∼27 kDa, D = 3 μm^2/s), 2 s for 4xGFP-tagged β-galactosidase (MW ∼580 kDa, D = 0.8 μm^2/s), and 75 s for 25–50 MDa ribosome-loaded mRNAs (D = 0.02 μm^2/s) to transverse the cytoplasm (primary source). Given the average doubling time of E. coli (∼30 min), even the largest macromolecular assemblies can travel back and forth multiple times during one cell division cycle. Osmotic stress will increase these times and progressively affect biological reactions that rely on fast macromolecular diffusion."
Entered by Uri M
ID 116217