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Re: [ccp4bb] itc equipment |
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CCP4bb navigationCCP4bb <-- 2007 <-- December 2007 <-- 06 December 2007Subject: Re: itc equipment From: Brett Collins b {- dot -} collins {- at -} IMB {- dot -} UQ {- dot -} EDU {- dot -} AU Date: 2007-12-06 We have just purchased a new iTC200 but are still waiting for it to arrive. I can update you when we've done some experiments in the new year to compare with the old Microcal. As you say we were attracted due to the reported low sample useage. You will have to realise though that these are idealised numbers thye are quoting. For example for the VP-ITC they say you only need 1.4 ml to fill the sample cell and 0.3 ml to fill the syringe. In reality you need to use about 1.8-2.0 ml and 0.4-0.5 ml to avoid bubbles etc. They gave us some numbers but I can't remember them exactly, but I think the iTC200 will realistically need about 0.3 ml to fill the cell rather than 0.2 ml. My estimate would be you'll need about 1/4 to 1/5 of the sample volume of the VP-ITC realistically. Which is still a huge improvement though. They also claim that the iTC200 will be equally sensitive using the smaller volumes but I guess we'll need to wait and see. I did get some info from Microcal when I asked them about a specific system we're studying which has a tight binding affinity (about 5 nM). The basic answer was that the only situation where the VP-ITC might be better is when you are dealing with a binding response that is about 1 nM and has a low deltaH response (i.e the binding has a very high c-value). In this case you would need less volume in the iTC200 but it would need to be more concetrated (say about 3 fold). I will say that I have a lot of trust in Microcal and I have confidence that this instrument will do pretty much what they say it will (and I'm not being paid honest). Feel free to contact me again in the new year when we should have some comparative data. Cheers, Brett On Thu, 6 Dec 2007 11:29:48 -0800 Engin Ozkan >Fellow crystallographers and biochemists, > > This will be off topic. Does anyone have any experience >with the new ITC Microcal is selling (itc200)? They >claim that itc200 requires one seventh the sample >volumes. We're especially interested in an equipment >that would require less sample without sacrificing >signal. We've had difficulty obtaining such information >from MicroCal or other sources. > > Engin > ----- > Stanford University School of Medicine > Molecular and Cellular Physiology CCP4bb navigationCCP4bb <-- 2007 <-- December 2007 <-- 06 December 2007 |
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