Re: Glutaraldehyde: a different kind of cautionary tale

From: Richard Knoppow ^lt;[email protected]>
Date: 05/03/04-07:38:59 PM Z
Message-id: <006501c43178$956be810$87fe5142@VALUED20606295>

  Lots of snipping...
> of the more prevalent sugars (18% of total sugar content)
in the gum.
> I was thinking this might explain why chrome alum didn't
work very well
> when I was doing my gum-hardening experiments for
painting, because of
> the relatively low proportion of carboxyl groups in the
gum (relative to
> gelatin). But how to explain why glyoxal worked very well
to harden gum,
> when there are even way fewer amine groups available in
gum than
> carboxyl groups? Either glyoxal links to something other
than amine
> groups in crosslinking gum, or..... it makes a great lot
out of a very
> few amine groups, or.......something.
> I didn't (and probably won't, given my history with this
substance) try
> hardening gum with glutaraldehyde. It would be interesting
to see
> whether it works as well as glyoxal. Since there are very
few amino
> groups, (and of those little and none is lysine and
hydroxylysine which
> are said to be the two amino acids that link in
glutaraldehyde hardening
> of gelatin)-- if glutaraldehyde works for gum, it must
work by an
> entirely different mechanism, or...... something.
> I think all this shows is that the chemistry of gum
crosslinking is
> probably quite different from the chemistry of gelatin
> which I already knew, and I wish to goodness people would
stop telling
> me that if I would only read this or that about gelatin
hardening, I
> would know all I need to know about the chemistry of the
gum process.
> Sorry, I don't THINK so!
> Katharine Thayer

 Was there also a large difference in pH? That might have
an effect. Chrome alum likes to work in an acid environment,
glutaraldehyde in alkaline.

Richard Knoppow
Los Angeles, CA, USA
Received on Mon May 3 19:39:13 2004

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