Hmmmm..the real message from figure 3. The protein concentration. seems to be that >70% of proteins do NOT crystallize in the 10-12.5 mg bin,
i.e. the 'right' concentration is an individual protein-in-that-buffer property - and all one can say is that the concentration needs to be high enough so that the crystallization conditions (either right away in case of batch, or vapor-diffusion assisted) can drive the system across the solubility limit into supersaturation. Most people actually working with their protein have already a reasonably developed idea what their protein can take in various buffer systems (valuable parameter!) . once they have scraped if off a centricon membrane, for example. The pre-screening originated from structural genomics when one had no idea what the 'customer' actually sent to the facility. If one knows the material it might be more efficient (i.e. more information from the same precious material) to set up a plate of 96 20+20 nl nanodrops than spending 2 ul on prescreening. Just an opinion sans statistics, BR From: CCP4 bulletin board [mailto:CCP4BB@JISCMAIL.AC.UK] On Behalf Of Debasish Chattopadhyay Sent: Tuesday, June 11, 2013 1:02 AM To: CCP4BB@JISCMAIL.AC.UK Subject: Re: [ccp4bb] Protein concentration for crystallization Perhaps my question was not expressed well. I wanted to know if proteins crystallize more frequently when the protein concentration is in the range 5-30mg/ml. The answer pointed out by my colleague Todd Green is on the page http://www.douglas.co.uk/PDB_data.htm Thanks for your inputs. Debasish From: Orru, Roberto [mailto:roberto.o...@emory.edu] Sent: Monday, June 10, 2013 5:04 PM To: Debasish Chattopadhyay Subject: RE: Protein concentration for crystallization Dear Debasish, On my memory there are 2 way (but I cannot say that are the only 2!) First: if you have the structure and you know the water content, you can guess the amount of protein crystallized in your drop by calculating the volume of the crystals. Second (if you can waste your drops): Fish all the crytsals in any drop for a given concentration, load a sds page w/ silver staining developing and compare it with a calibration curve done with your same protein in the same gel. Best R. _____ From: CCP4 bulletin board [CCP4BB@JISCMAIL.AC.UK] on behalf of Debasish Chattopadhyay [debas...@uab.edu] Sent: Monday, June 10, 2013 10:49 To: CCP4BB@JISCMAIL.AC.UK Subject: [ccp4bb] Protein concentration for crystallization What would be a convenient way to estimate what percentages of proteins have been crystallized in a concentration range, for example 5-30 mg? Debasish Chattopadhyay University of Alabama at Birmingham CBSE-250 1025 18th Street South, Birmingham, Al-35294 USA Ph: (205)934-0124; Fax: (205)934-0480 _____ This e-mail message (including any attachments) is for the sole use of the intended recipient(s) and may contain confidential and privileged information. If the reader of this message is not the intended recipient, you are hereby notified that any dissemination, distribution or copying of this message (including any attachments) is strictly prohibited. If you have received this message in error, please contact the sender by reply e-mail message and destroy all copies of the original message (including attachments).
