As you say, the primary structure can be cloned. What characterizes
conotoxins are actually the number of S-S bridges formed between Cystein
residues, and the number of resulting loops serves as classification
criterion:alpha conotoxins, omega conotoxins, mu conotoxins, etc.
Conantokins are simpler variations, currently under study. In principle,
there are a number of chemical procedures for the formation of S-S bridges
in peptidic chains. I do not see this much of a problem for the synthesis,
specially considering that they are relatively lightweight and simple in
comparision with other far more complex proteins.
Lots of useful information about conotoxins can be found at Bruce Livett´s
great web site: http://grimwade.biochem.unimelb.edu.au/cone/
Warmest regards

Manuel Jimenez Tenorio


On Thu, 30 Jun 2005 16:08:04 -0700, Stemke Douglas <[log in to unmask]>
wrote:

>A quick question.  While the conotoxins aren't all that large, if I
recall correctly, at least some of them are circular (the first amino acid
(C terminal) attaches to the last amino acid on the N terminal side).
Does this actually make synthesis of these peptides particularly difficult?
>
>I suspect at least the primary peptide sequence (linear) could be cloned
into the chromosome or plasmid of our old friend E. coli (bacteria) and
then simply over expressed in that organism. Provided the peptide isn't
lethal to the bacteria it can simply be grown in a fermentor, and these
fermentors are huge (thousands of liters) .  This would be far more
economical then trying to isolate the peptides from tens of thousands of
cones.
>
>

----------------------------------------------------------------------
[log in to unmask] - a forum for informal discussions on molluscs
To leave this list, click on the following web link:
http://listserv.uga.edu/cgi-bin/wa?SUBED1=conch-l&A=1
Type your email address and name in the appropriate box and
click leave the list.
----------------------------------------------------------------------