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[yuanhenglidlut]

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[musgun]

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[yuanhenglidlut]

Originally Posted by musgun

I agree with AplaGen. Capping agents and pseudo-prolines increase the success and the yield of difficult sequences greatly. I had a 42 resiudes long peptide with which I always got tens of peaks at the HPLC. When I used a capping agent and psuedo-prolines at certain positions, all problems were solved.

Excuse me~
Capping agents or coupling agents?

What coupling agents do you always use?

We often use DIC/HOBt(2.5eq), for the Fmoc-AA-OH difficult to couple,we usually use PyBop(2.5eq)/HOBt(2.5eq)/DIPEA(5eq) for recoupling. I donot know if this will help to the final product. The Kaiser Test showed the completeness of coupling.

[musgun]

Originally Posted by yuanhenglidlut

Excuse me~
Capping agents or coupling agents?

What coupling agents do you always use?

We often use DIC/HOBt(2.5eq), for the Fmoc-AA-OH difficult to couple,we usually use PyBop(2.5eq)/HOBt(2.5eq)/DIPEA(5eq) for recoupling. I donot know if this will help to the final product. The Kaiser Test showed the completeness of coupling.

No it is capping (or terminating) agent, such as N-(2-Chlorobenzyloxycarbonyloxy)succinimide. It terminates the unreacted amine groups.

But I think pseudo-prolines might help better than capping agents in your case. Try putting pseudo-proline di-peptides at the positions where you think the coupling is failing. They help by acting like a proline and preventing the peptide to fold during the coupling. You can find more info at http://www.emdbiosciences.com/html/N...dotheywork.htm