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Figure 5
Calculated molecular weight (cMW) versus concentration for PEG 8K (a) and ammonium sulfate (b). The calculated molecular weight is the molecular weight of all of the atoms in the asymmetric unit after removing the waters. Ammonium sulfate is used both as an additive and as a precipitant and it is unclear where it stops being an additive and starts being a precipitant. The ammonium sulfate chart only shows data where ammonium sulfate concentrations of greater than 0.2 M were included. The cutoff of 0.2 M was chosen as the commercial screens tend to classify 0.2 M or less as a `salt' or `additive' and higher concentrations as `precipitant'. When ammonium sulfate was found as a `%' unit, we calculated the equivalent molarity using 4.8 M as the saturation point at room temperature (i.e. 100%). There was no correspondingly obvious cutoff for PEG 8K used as a precipitant.

Journal logoBIOLOGICAL
ISSN: 1399-0047
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