Q: BSA fraction V for Church-Gilbert's solution

David F. Spencer dspencer at is.dal.ca
Thu Jul 17 11:03:24 EST 1997

In article <13899944986 at dna.cbiot.ufrgs.br>, diego at DNA.CBIOT.UFRGS.BR
(Diego Bonatto) wrote:

> Hello:
>   I have one question about BSA fraction V: there are a lot of BSA 
> fraction V that differ in its purification process only (Sigma 
> catalog and others). I want to make the Church-Gilbert's solution for 
> Northern Blot, so what BSA fraction V  (Cohn process, Cohn Method 4, 
> Heat-shocked fractioned, etc...) I will need to make this solution? 
> There is some influence of purification process in the BSA fraction V 
> itself? Or not? 

Given the cost of this material I would recommend the least expensive (that
being about 90 cents US per gram).  The different fractions reflect how
much contaminating protein or fatty acids are present and presumably how
much protein  denaturation occurred during the fractionations.  Given that
this is going to be used as a blocking agent for hybridizations I can't
imagine any of these factors are relevant.

A far less expessive and equally effective blocking agent is non-fat
instant skim milk powder (in the US and Canada sold by Carnation) which was
originally given the acronym 'BLOTTO' (when combined with SDS) by its first
proponents (Johnson et al., Gene Anal. Techniques 1:3-8 (1984) ) and
described for use in Northerns (after DEPC treatment) by Siegel and
Bresnick, Anal. Biochem. 159:82-87 (1986).  I use and advocate the use of
BLOTTO to anyone doing Southerns or Northerns.

Dave Spencer

David F. Spencer, PhD
Dept. Of Biochemistry
Dalhousie University
Halifax, Nova Scotia

dspencer at is.dal.ca
dspencer at rsu.biochem.dal.ca

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