5 replies to this topic

[valeri_a]

HI, I need hypotonic homogenization buffer, and I want to know if I can replace MOPS for any similar compound,

thank u !!

[mdfenko]

do you know why mops was selected in the first place? sometimes buffers are selected for reasons besides their pK.

if mops was selected only for its pK then you can use any buffer with the same or similar pK (i'm not at work so i don't have access to my list or i would make some suggestions).

[phage434]

MOPS has a pKa of 7.2.  Similar buffers with close pKa include HEPES (7.5) and PIPES (6.8).  Even Tris might be used (pKa about 7.5) but it has primary amines, which can be an issue in some reactions.

[valeri_a]

yes, that`s right. HEPES has similar pKa . I think would be fine if I use HEPES in place of MOPS.  

thank you mdfenko and phage434!

[mdfenko]

phage434, on 23 November 2012 - 08:21 PM, said:

MOPS has a pKa of 7.2.  Similar buffers with close pKa include HEPES (7.5) and PIPES (6.8).  Even Tris might be used (pKa about 7.5) but it has primary amines, which can be an issue in some reactions.

for the record, tris has a pK of 8.2 (or 8.14 or 8.1, depending on where you look), hepes is 7.55.

bes has a pK of 7.15.

which buffer you select should also take into consideration the direction of change to be resisted (ie will it be getting more acidic or basic if not buffered), then select a buffer with a pK in that direction from the starting pH.

here is a page from sigma with information on good's buffers.

Edited by mdfenko, 26 November 2012 - 06:42 AM.

[El Crazy Xabi]

Many buffers used in biology are usable at that pH, e.g. SIgma list
http://www.sigmaaldr...nce-center.html

By homogenization do you mean lysis?

All depends want do you are going to do. Some buffers may interfere with some applications/procedures.