Off Topic: Isothermal Titration Calorimetry (ITC)

From: Jose Artur Brito
Date: 17 January 2012 16:02

Dear All,
sorry for this off-topic questions but I would like to have some feed-back from you on Isothermal Titration Calorimetry (ITC) equipments.
We have a very nice quotation for an iTC200 from GE Healthcare. We wanted this one because it uses ~200uL sample per measurement (really nice when your dealing with "precious" samples, ie., proteins with low expression yields). However, I was told that, although consuming much less sample, is not as good (sensitivity, mixing issues, bubbles, ...), as the VP-ITC (it uses ~1.4mL per measurement, seven times more than the iTC200).
Does anyone has experience with these two equipments? Would you prefer one over the other (please state your reasons)? Would you suggest another equipment/brand for the ITC (like the NanoITC from TA Instruments)?
Thanks in advance,
Jose Artur Brito

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* José Artur Brito, PhD       

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From: Scott Thomas Walsh


Dear Jose,

I have an iTC200 in my lab and have experience with a VP-ITC.  The major problem with
the iTC200 is that GE has not increased the sensitivity of the instrument.  Thus, you must use
higher concentrations in both the cell and syringe to see measurable heats. The syringe on the
iTC200 holds 40 uLs.  The other issue is the quality of the products from GE.  I have replaced
2 boards on the instrument and replaced the washing module.  GE manufacturing is going down
hill and there equipment is really expensive.

I would really consider demoing TA instruments.  I have done this for purchase of a capillary DSC
instruments.  TA instruments quoted me $75,000 for their cap DSC.  The similar cap DSC by GE was
quoted for $150,000.  We are purchasing the cap DSC from TA instruments.  In retrospect, I should have
done the same thing for the ITC instruments.

Cheers,

Scott

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Scott T. R. Walsh, Ph.D.

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From: Michael Hothorn


Dear Jose,

I used both instruments for a number of years, first the VP ITC and later on the ITC 200. I personally find the ITC 200 much more demanding to operate. I think Microcal managed to improve the sensitivity of the ITC 200 about 2-3 fold compared to the VP ITC, but they decided to decrease the volumes by a factor of 6-7. This means that you have to work at higher sample concentrations in the cell and in the syringe to get decent signals. In addition the instrument is rather fragile (especially the glass syringe) and more difficult to clean and maintain. I decided to go back to the VP ITC. I cannot comment on other instruments.

best wishes
Michael

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From: Scott Pegan


Dear Jose,

Last year we acquired a TA instruments nanoITC after evaluating it and a Microcal model.  For the price, the TA instrument was a considerable steal, was ~$50,000 cheaper the the Microcal Model.  We didn't see or have since seen any issues with quality of the instrument.  Software between the two differ does differ.  TA instruments has a nice prediction model to assist with setting up the experiment, but is just in the throws of getting all the models put into practice for their analysis software (they provide all of their updates for free).  Where as Microcal has a mature analysis software, but lacks the prediction component.

Scott

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Scott D. Pegan, Ph.D.

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From: Philippe DUMAS


Dear all,
We have good experience with the ITC200 and we do not consider as a real limitation the consequence of the small volume. In fact, this is not only the absolute amount of heat to be measured that is important because such microcalorimeters measure a power in µcal/s. This is where another factor, the time response of the instrument, is important because a longer time response (10 s for the VP-ITC and 3.5 s for the ITC200) 'dilutes' the signal and lowers the measured power.
See simulations on our web site:
http://www-ibmc.u-strasbg.fr:8080/webMathematica/kinITCdemo/index.jsp

In addition, a smaller time response going with a smaller cell volume is very favourable for using our newly developed kinITC technique. Again, see our web site and also JACS 134(2012)559.

Last, but not least, you need much less material and much less time for doing experiments with an ITC200 in comparison of what is needed with a VP-ITC.!!!
We have no experience with TA instruments.

Philippe DUMAS, responsable d'équipe
Directeur de Recherche au CNRS

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From: Stephen Graham


We bought a NanoITC from TA instruments last year and I can't
recommend it enough.  We are able to get excellent binding curves with
the low volume cell/syringe (200uL/50uL, respectively, which actually
means 350uL/120uL in order to load both without bubbles) using the
same concentrations of protein as we used to use in a MicroCal VP-ITC.
 The control/analysis software is much easier to use (although the
graphing capabilities could be improved) and the technical support has
thus far has been excellent.  Also, as others have said it's a steal
compared with the equivalent GE machine (both in terms of purchase
cost and cost of maintenance contracts).

Stephen

--
Dr Stephen Graham

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From: krish


I second Stephen's comments on NanoITC. I haven't seen any improvement in terms of volume. The total volume one should use is very much comparable to MicroCal VP-ITC. Analysis software is OK--not so good--crashing some times--GUI needs to bit robust in handling the data.

HTH !

Krishna Chinthalapudi
Hannover Medical School

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From: SnowDeer

Dear Joes:

 

I have used both ITC200 and VP-ITC. In my opinion, the VP-ITC is better than the former one.

Although ITC200 needs less samples, the sensitivity is lower than VP-ITC. Furthermore, the syringe of ITC200 is too easy to be broken and the price of it is very high~~ You need a experienced person to change it.

 

Best wishes,

Xuelu