||"Physical Biology of the Cell", Rob Phillips, Jane Kondev and Julie Theriot (2009). Page 110
||D calculated according to Einstein-Stokes equation D=KBT/6/pi/?/R where R=2.5nm, typical protein radius. KB=Boltzmann's constant, ?(eta)=viscousity of the medium, taken as 0.001 Pa*sec for water at ~300 Kelvin, T=temperature in degrees Kelvin, pi=~3.14. (1.380?6504(24)×10^-23Kgm^2 sec^-2K^-1×300K)/(6×3.14×0.001Kgm^-1sec^-1×2.5× 10^-9 m)=8.8 × 10^-11m^2/sec= 88µm^2sec=~100µm^2/sec
||Radius of ~2.5 nm can be calculated by taking 100KDa and 1200 Kg/m^3 as mass and density, respectively, of typical globular protein. This gives radius of ~2.2nm. In cytoplasm D is smaller than 100µm^2/sec as there are solutes.