I use TBTU coupling reagent (or some others) and not the combination
you've mentioned, however it should be the same reaction time and
conditions;
1) I don't keep a solution of TBTU/DIEA for more than 1-2 days (you can
see
the dark yellow colour that evolve). I can advise you to weight the
reagents, keep it dry (and cold), and dissolve it just before the
coupling.
2) Let the coupling proceed for 2 hr. and check it after washes. More than
2 hr. is usually not efficient.
3) 10 min. of an activation is recommended.
Good luck,
Ron Kasher.
On Thu, 15 Jan 1998, MARIA THYBOLL wrote:
> We are going to do a manual solid phase peptide
> synthesis and will use HBTU/HOBt/DIEA
> to form esters and to couple amino acids together.
> The ratios we thought to use is
> 1:1:1:2 (Fmoc-aa/HBTU/HOBt/DIEA) in DMF.
>
> I have two questions about the coupling reaction.
>
> Does anyone have any suggestions about how long
> the reaction time shall be, if you want to form
> an ester bond or a peptide bond?
>
> Can a stock solution of HBTU/HOBt/DIEA
> in DMF be made, to which you add the amino acid
> when youwant to make the coupling step?
> When you have added the amino acid, shall you let the
> solution activate for a while before adding it to the
> solid phase. If that's the case, how long should the
> activating time be?
>
> If you can make up the above mentioned stock solution,
> does somebody know for how long it will be stable?
>
> If there is any other information about the reagents that
> you want to share, please do so.
>
> Best regards Maria Thyboll
> Maria Thyboll
> Department of Analytical Chemistry
> Royal Institute of Technology
> Teknikringen 36
> 100 44 Stockholm
> SWEDEN
> Tel +46 8 7906410
> Fax + 46 8 108425
> Email k93_mtl@k.kth.se
>
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Ron Kasher
Department of Organic Chemistry
The Hebrew University of Jerusalem
Jerusalem, 91904 Israel.
Tel: 972-2-658 6181
Fax: 972-2-658 5345
e-mail: ronk@shum.cc.huji.ac.il