[Demelerlab] AUC Collaboration: Sizing Amyloid Beta derived Oligomers

[James S. Nowick]

Hi All,

The bottom line is that the absorbance of trifluoroacetate should be negligible with respect to the peptide. The peptide absorbs so strongly at 214 nm that you will need to go to longer wavelengths. Alternatively, I think interference optics might be a good option.

Best,
James


> On Jul 18, 2023, at 7:57 PM, Jason Zhu <jasonz13 at uci.edu> wrote:
> 
> Hi Borries and James,
> 
> I tried running different TFA concentrations on the nanodrop and got very noisy UV-Vis spectra that I don't fully trust. I enabled the automatic baseline correction and automatic pathlength adjustment settings on the nanodrop which seems to have helped with the negative absorbance values that don't make physical sense. I will meet with James tomorrow morning and will work out the details of getting accurate absorbance values for both TFA and F19Cha then.
> 
> <image.png>
> 
> I plan on weighing out the peptides, labeling them, and shipping them by the end of the day Wednesday (tomorrow). I'll send an update once we figure out the ideal wavelength for the different concentrations we plan to run at each concentration and when the peptide is on its way.
> 
> For lyophilized powder, 4C should be adequate. F19Cha isn't prone to oxidizing from my experience working with it.
> 
> Best,
> Jason
> 
> On Tue, Jul 18, 2023 at 2:38 PM Borries Demeler <demeler at gmail.com <mailto:demeler at gmail.com>> wrote:
>> Hi Bruce and Ariel:
>> We would like to have some samples shipped to U of Montana, and I would like to pick them up on Friday, if this is possible? The samples are lyophilized peptide samples and can probably be stored at 4C. I will be in Missoula on Friday  and Saturday, all day, our entire lab will actually be in Missoula for a vaccine development workshop with the CTM group. Thanks for helping again with the samples!!
>> 
>> James and Jason:
>> Regarding the sample shipment, you can overnight them as a lyophilized powder to:
>> 
>> University of Montana
>> Dept. of Chemistry &Biochemistry
>> c/o Bruce Bowler or Ariel Frederick
>> 23 Campus Drive
>> Missoula, Montana 59812
>> 
>> Please weigh them out and indicate on your shipping list with what volume they need to be suspended to get the desired concentrations. Our loading volume will be 110 ul, and we would like to know the wavelength to use where we would get 0.6 OD in a 3 mm pathlength centerpiece, with no more than 0.3 OD of background absorbance from the buffer (when blanked against water). We can use different wavelengths for each sample to optimize the absorbance for each concentration.
>> 
>> The speed will be 60 krpm, so they should be measured in the An60Ti rotor, at 20C.
>> 
>> Please ship so they will be available for pickup by us on Friday this week. Please indicate the storage conditions - I assume for the lyophilized powder 4C is adequate?
>> 
>> Thanks, -Borries

James S. Nowick
Distinguished Professor
Department of Chemistry & Department of Pharmaceutical Sciences

Department of Chemistry
4126 Natural Sciences 1
University of California, Irvine
Irvine, CA 92697-2025

Phone:  (949)  824-6091
e-mail: jsnowick at uci.edu
Faculty Web Page: http://tinyurl.com/jsnowick/
Research Group Web Page: http://tinyurl.com/nowickgroup/
Pronouns: he/him/his

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