Hi there,
I disagree with DK since molarity of buffer can not be calculated as a sum of two component. Lets take MES acetate as an example. 1 M buffer means that there is one mole of MES in 1 L of buffer whose pH is adjusted with acetic acid. Concerning tris hepes buffer - is it possible that your colleague meant that you can use either tris or hepes? otherwise, you can dissolve hepes to be 50 mM and adjust pH with concentrate solution of tris (tris solution is by itself very basic - pH ~11), or other way around but i can not remember any explanations why anyone would use that buffer. best wishes, N.L. ________________________________ From: "[email protected]" <[email protected]> To: [email protected] Sent: Tuesday, February 7, 2012 6:07 PM Subject: Methods Digest, Vol 81, Issue 2 Send Methods mailing list submissions to [email protected] To subscribe or unsubscribe via the World Wide Web, visit http://www.bio.net/biomail/listinfo/methods or, via email, send a message with subject or body 'help' to [email protected] You can reach the person managing the list at [email protected] When replying, please edit your Subject line so it is more specific than "Re: Contents of Methods digest..." Today's Topics: 1. Tris-HEPES (Yvonne Couch) 2. Re: Tris-HEPES (DK) ---------------------------------------------------------------------- Message: 1 Date: Mon, 6 Feb 2012 15:31:15 +0000 From: Yvonne Couch <[email protected]> Subject: Tris-HEPES To: "[email protected]" <[email protected]> Message-ID: <fc9d052c4a50c04e8d6c54d2f870a5819380041...@exmbx01.ad.oak.ox.ac.uk> Content-Type: text/plain; charset="us-ascii" Hi all, I am trying to replicate the experiments of an ex-colleagues whose notes require '50mM tris-HEPES buffer (ph7.5)'. I am not sure whether the 50mM refers to the tris or the HEPES and was wondering whether anyone had any experience with this? I am using it as an extraction buffer for fresh tissue (the other components of which are sucrose and EDTA) and need to maintain the integrity of the enzymes within the tissue, rather than the cells. If anyone has any suggestions for a replacement for this buffer or any more details on how to make a tris-HEPES buffer, I would be most grateful. Regards Yvonne ------------------------------ Message: 2 Date: Tue, 07 Feb 2012 02:18:25 GMT From: [email protected] (DK) Subject: Re: Tris-HEPES To: [email protected] Message-ID: <QR%[email protected]> In article <[email protected]>, Yvonne Couch <[email protected]> wrote: >Hi all, >I am trying to replicate the experiments of an ex-colleagues whose notes > require '50mM tris-HEPES buffer (ph7.5)'. I am not sure whether the 50mM > refers to the tris or the HEPES and was wondering whether anyone had any > experience with this? There is plenty of ambiguity there but I'd think that it means that the buffer is made with 25 mM of Tris and 25 mM of HEPES. At least that's how it works in our lab: a "1.0 M MES-Acetate" is 0.5 M of each component. > has any suggestions for a replacement for this buffer It's going to be a very good buffer at 7.5. Lots of things could work as replacement though. >or any more details on > how to make a tris-HEPES buffer, I would be most grateful. Mix HEPES (free acid form) and Tris (free base form) and adjust pH to 7.5 with either NaOH or HCl (I am not sure what pH is going to be when mixing equal concentrations of HEPES and Tris). DK ------------------------------ _______________________________________________ Methods mailing list [email protected] http://www.bio.net/biomail/listinfo/methods End of Methods Digest, Vol 81, Issue 2 ************************************** _______________________________________________ Methods mailing list [email protected] http://www.bio.net/biomail/listinfo/methods
