In article <Pine.SOL.3.91.960618122709.16948D-100000 at howard> Patrick <patrick at howard.genetics.utah.edu> writes:
>Path: magnus.acs.ohio-state.edu!math.ohio-state.edu!cs.utexas.edu!news.cs.utah.edu!news.cc.utah.edu!howard!patrick
>From: Patrick <patrick at howard.genetics.utah.edu>
>Newsgroups: bionet.microbiology,bionet.general,sci.bio.microbiology
>Subject: Re: streptomycin precipitation question
>Date: Tue, 18 Jun 1996 12:31:55 -0600
>Organization: University of Utah Computer Center
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>On Wed, 12 Jun 1996, M.C. Bean wrote:
>[...]
>> In our laboratory we are currently using streptomycin sulfate to precipitate
>> membranes as part of a purification procedure. This certainly seems to work
>> and is mentioned passing is a couple of papers we have. The trouble is we
>> don't have any idea why it works. Does anyone out there know? Are there any
>> papers describing the mechanism?
>[...]
>I cannot offer an answer but only another question. Streptomycin sulfate
>can also be used to precipitate DNA. Myself and a colleague attempted to
>divine how this would work since DNA is itself a negatively charged
>molecule under the general conditions used for the precipitation. I can
>try to re-examine the conditions of the precipitation (perhaps they
>favor complex formation between DNA, Na, and strep sulfate?) but if
>anyone can answer the question - what is the mechanism of strep sulfate
>precipitation of DNA? - I would be grateful.
>patrick
The probability is that streptomycin binds (by its amino groups) to the
phosphate groups of membrane phospholipids just as it binds to the
phosphates of nucleotides. By this mechanism it would aggregate membranes. It
also aggregates micelles of phospholipids. In this respect it resembles
calcium. Many years ago (1960's) we were able to infect E. coli protoplasts
with naked nucleic acid of PhiX 174. I don't have references at hand but I
would look at the literature (especially Membrane BBA in the early middle 60s)
A. Ottolenghi
