I conjugate the Peptide with NOTAGA. Then i tried NOTAGA-Peptide labeled with In-111.It is like In-111-NOTAGA-Peptide. When i want to do the serum stability assay. After one hour the Peptide is decompose(according the HPLC)
Is there anyone can tell me how to make the peptide more stable ?
Thank you.
Is the Indium-111 forming a non-covalent complex? It might be falling apart under acidic conditions used in RP-HPLC (i.e. nothing to do with stability in serum).
How do you know that your peptide decompose?
Simple HPLC will be hardly capable of telling you what is happening with a conjugation complex such as NOTA.
Do you see any other peaks appearing ?
@toan tran Thank you for your answering.I stored NOTA-Peptide solution in 4 degree.
@viswanatham Katta thank you for you reply.I think there is no relationship with the Chelate NOTA with Non-covalent or not. Yeh, Firstly, added In-111-NotaGA-peptide into the serum ,secondly,add acetonitrile. And centrifuge.
@Fabrizio Donnarumma Because i compare with different time about the HPLC. 0hour 1 hour and 3 hour3.The Peak is decrease.....
Yeh at first like around 2 mins there are 2 peaks. But i dont know whats that.
Then we can say that your whole conjugate signal decreases.
And some additional peaks appear.
My guess is that the DOTA+ peptide is the stable part of your complex. If anything, the metal might slip out or be exchanged with different ions.
I saw this furing my master thesis work. I was synthesizing a DOTA macrocycle and creating a conjugate with gadolinium. It often happened that the Gd was replaced by Calcium, for example.
Can you provide the following:
- Storage condition (solvent) used for the final conjugate
- Storage conditions for the spiked serum sample
In addition, did you analyzed the samples with an autosampler? If yes, did you put a vial in and run it every hour or so?
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