# Minimal radius for proteins of different mass

Range Table - link nm Generic Erickson HP. Size and shape of protein molecules at the nanometer level determined by sedimentation, gel filtration, and electron microscopy. Biol Proced Online. 2009 May 15 11: 32-51. doi: 10.1007/s12575-009-9008-x. p.34 table 1PubMed ID19495910 "Assuming this partial specific volume (v2=0.73 cm^3/g BNID 110540), [researchers] can calculate the volume occupied by a protein of mass M in Dalton as follows. Vnm^3=[(0.73cm^3/g)X(10^21nm^3/cm^3)/(6.023X10^23Da/g)] X M(Da)=1.212X10^-3nm^3/Da X M(Da). The inverse relationship is also frequently useful: M (Da)= 825V (nm^3). What [researchers] really want is a physically intuitive parameter for the size of the protein. If [they] assume the protein has the simplest shape, a sphere, [they] can calculate its radius. [They] will refer to this as R min , because it is the minimal radius of a sphere that could contain the given mass of protein Rmin= (3V/4p)^(1/3)=0.066M^(1/3) (for M in Dalton, Rmin in nanometer)." "Some useful examples for proteins from 5,000 to 500,000 Da are given in Table 1. It is important to emphasize that this is the minimum radius of a smooth sphere that could contain the given mass of protein. Since proteins have an irregular surface, even ones that are approximately spherical will have an average radius larger than the minimum." Uri M 110541