Hi,
pure sodium phosphate or pure potassium phosphate are not as soluble as
the mix of both. Especially if you crystallize at temperatures below
20°C you will get a lot of salt crystals.
I used 2.5 M or 2.0 M stocks of Na2HPO4 and KH2PO4 (or the other way
round, i.e.NaH2PO4 and KH22PO4) and adjusted final concentration with
water. I anm not sure about the ration in commercial screens, but might
be 1:1. So simply try 1:0.9; 1:0.8 .... and different final
concentrations of phosphate.
As far as I remember my hit was extremely temperature sensitive.
HTH
Guenter
Dear all,
Quite a few crystallisation conditions in the screens feature
'sodium/potassium phosphate'. I'm curious to know why such a Na/K mix
is there. As the pH is mostly determined by the (H2PO4)- to (HPO4)2-
ratio, is there such a need to have both cations? If so, is the Na to
K ratio important?
On the more practical side of things, if you want to explore an
initial hit based on sodium/potassium phosphate, how would you go
about it - e.g. what phosphate buffers would you make and at what
ratio would you mix them?
Thanks in advance,
Geoffrey Kong
--
***********************************
Priv.Doz.Dr. Guenter Fritz
Fachbereich Biologie
Sektion Naturwissenschaften
Universitaet Konstanz
http://www.biologie.uni-konstanz.de/fritz
Universitaetsstrasse 10
Postfach M665
D-78457 Konstanz
e-mail: guenter.fr...@uni-konstanz.de
Tel. Office: +49-(0)7531 88 3205
Tel. Lab : +49-(0)7531 88 3687
Fax: +49-(0)7531 88 2966
