Dear Ray, The solubility and stability effect of glycerol is protein dependent and highly concentration dependent. When used at the wrong concetration or molar ratio to protein, preferential interaction could result in adverse effects. Likewise at concentrations higher than 15% in drops for crystal growth, the protein could remain under the solubility curve of the phase diagram for a long period. This is particularly the case when preciptant concetration is not balanced with glycerol concentration used.
Generally, sugar alcohols, which glcerol is one, are well documented as excellent protein stabilizers (protect protein against proteases in solution, against thermal denaturation, to some extent reduce conformational flexibility and increased molecular contacts in solution based on its viscosity and experimetally determined effect on chemical potential/hydration on protein surfaces; see Biochemistry 1982, 21, 6536-6544 and others). However, the right concentration or molar ratio to have the desired effect on protein needs to be determined a priori, especially when used as an additive in drops for protein crystal growth. 10% glycerol is approx 1M and help solubiize as well as stabilize most protein sufficiently during preparation and storage. >From my little experience and literature knowledge, when used as additive in crystallization, concentration series need to be screened together with the preciptant of choice, and I would recommend 0.1M a safe starting point. all the best. Ade On Thu, March 10, 2011 23:04, Ray Brown wrote: > Hi all, > > I was intrigued by the recent question of whether glycerol had any adverse > effects on the final purity of protein isolated by chromatography. > Glycerol > certainly helps to solubilize some proteins. Does anyone know of any > negative > effects of glycerol in protein purification, on protein crystal quality or > use in cryocrystallography and on X-ray diffraction results? > > Cheers. > > Ray Brown -- Adekunle Onipe, PhD Student Djinovic-Carugo Group Dept of Structural and Computational Biology University of Vienna | Max F. Perutz Laboratories Dr Bohrgasse 9 | A-1030, Vienna, Austria.
