We did some data mining from remark 280 of the PDB in 2004. Of the 1000 entries that listed [protein], 46 proteins were crystallized below 3.1 mg/ml. See table 3 at http://www.douglas.co.uk/PDB_data.htm .
Patrick On 27 February 2012 16:25, Bernhard Rupp (Hofkristallrat a.D.) < hofkristall...@gmail.com> wrote: > Why, in the first place, do you feel an urge to concentrate your protein > above 3 mg/ml ?**** > > ** ** > > For crystallization, the concentration needs to be **** > > **a) **high enough to achieve supersaturation, meaning close enough > to the maximum solubility in a given buffer so that the precipitant can > drive the system in to supersaturation, preferably of a level where > homogenous nucleation can occur (or you micro-seed, if necessary)**** > > **b) **high enough that sufficient material for crystals of > acceptable size to grow is in the drop, which is generally the case, lest > micro-crystal showers happen.**** > > ** ** > > There is ample evidence for proteins crystallizing below 3 mg/ml.**** > > ** ** > > The often quoted PDB/BMCD average of somewhere around 10 mg/ml is biased > towards highly soluble, smaller (lower hanging fruit) proteins.**** > > ** ** > > Sometimes the shape of a distribution matters ;-)**** > > ** ** > > BR **** > > ** ** > > *From:* CCP4 bulletin board [mailto:CCP4BB@JISCMAIL.AC.UK] *On Behalf Of > *Sangeetha > Vedula > *Sent:* Monday, February 27, 2012 8:02 AM > *To:* CCP4BB@JISCMAIL.AC.UK > *Subject:* [ccp4bb] Desalting columns**** > > ** ** > > Dear bb users, > > I am trying to crystallize a ~320 kDa protein that crashes out if > concentrated past about 3 mg/mL. > > I would like to try to exchange it into various buffer-salt-additive > combinations to see which buffer works. For a starting point, I'd like to > use desalting colums. > > Does anyone have suggestions for good buffer exchange and sample recovery? > I woud like to load about 250 uL onto each column. > > Thanks a lot! > > Best regards, > > Sangeetha.**** > -- patr...@douglas.co.uk Douglas Instruments Ltd. Douglas House, East Garston, Hungerford, Berkshire, RG17 7HD, UK Directors: Peter Baldock, Patrick Shaw Stewart http://www.douglas.co.uk Tel: 44 (0) 148-864-9090 US toll-free 1-877-225-2034 Regd. England 2177994, VAT Reg. GB 480 7371 36
