Acidic, volatile buffer for lyophilization

[larfab]

Hi,

 

I would need an acidic, totally volatile buffer for lyophilization of my protein. The pH should be 3.0. The best were an egzact recipe, and because the total volatility is necessery, I think it is not good if the adjusting happens with for example HCl.. At least after my opinion.. So, I would like to get only my protein after lyophilization. In the last time I tried to make an ammonium-acetate -acetic acid buffer, first I solved 3,9 g ammonium acetate in 300 ml water (I wanted to make 500 ml end-volume; 3,9 g ammonium-acetate gives 50 mM concentracion in 500 ml), then I added to it acetic acid to getting pH 3.0. But I had to add ~110 ml 97% acetic to pH 3.0, so "the buffer" was 20% for acetic-acid, which is a little bit high concentration I think.. I could't freeze this solution on -20°C. So, any idea, any probed acidic buffer which is common used at lyophilization with recipe?

 

Thx,

Larfab

[CharonY]

Ammonium acetate buffers a bit higher than what you need. However, Ammonium formate should be right in your range. The slightly tricky bit is actually what molarity the prootcol demands. Many protocols actually indicates the cation portion. In that case the above approach would be appropriate (just leave ample room to fill up to final volume). Sometimes total molarity is meant, in which case it refers to ammonium formate + formate.. In that case the easiest way is to approximate with the Henderson-Hasselbalch equation (though a little bit of adjustments is often necessary, regardless).

[BabcockHall]

I once lyophilized protein that had been dialyzed against 1 mM hydrochloric acid. I followed the lyophilization with complete hydrolysis of the protein. Perhaps 1 mM hydrochloric is not suitable for your protein, in which case ammonium formate sounds reasonable.