>The Matthews function is based on an average protein crystal with 50% solvent.
Not sure what that a 'Matthews function' exactly would be - and that an assumption of 50 solvent content is made anywhere in the Vm calculation is new to me. The only defensible prior that goes into the calculation of Vm is a fixed protein specific volume, for details see Quillin & Matthews 2000 Acta D56 791. The Matthews Probability calculator in addition considers the actual resolution and provides a probability distribution, i.e. the probability for each of the possible numbers of molecules in the unit cell. The more molecules are possible, the more indiscriminate the possible solutions become, i.e. the actual number needs to be determined by other, supplemental information. http://www.ruppweb.org/mattprob/ Best, BR
