Pleas Help Quick

Frank Fuerst fant.1 at
Fri May 5 03:00:23 EST 2000

Toby Skinner wrote:
> Hello, I have a simlpe question and I really nead an answer quick.

Ahm, you no that this isn't your private helpdesk?
> Any protein is made up of amino-acids, it is these that define the overall
> structure and therefore function of the protein.  I know that amino-acids
> can be replaced by other amino-acids without effecting the function of the
> protein.

> So if I was able to generate a new say, Haemoglobin protein which has a
> significantly different amino-acid content, does anyone know if (in theory)
> it could be created in the lab and experimented apon?  

In principle, yes. You can alter a considerable percentage of the
sequence (especially if your exchanges are conservative, i.e. the type
of amino acid [aliphatic, acidic etc.] is not changed) without mayor
effects on function and stability. But of course the really important
residues in the active site cannot be altered as long as you still
want your protein to function; in the hemoglobin case it would be at
least the ligands of heme, and additionally some residues necessary
for the cooperativity - otherwise you'll get a "tetrameric myoglobin".

Created in the lab?
genetic engineering, usually connected with heterologous expression
(in E.coli, S. cervisiae etc.), would be a reallistic approach.
Chemical synthesis of such a long polypeptide chain is not feasible.

> This is a serious
> question and has implications for some software I have written
> (dissertation) for finding amino-acid sequences which fold into the same
> user specified protein.  

My opinion is that everybody planning to write some bioinformatics
software should first carefully read and understand a textbook
specific for the relevant field (in this case, protein structure) and
know some biochemist to talk to...

> The idea is that a useful but toxic protein could
> be enginered in the lab to be non-toxic.

Toxicity of proteins often does not depend on the primary sequence,
but on the specific function of the protein. So your non-toxic protein
will probably no longer be usefull. There are some exceptions, e.g. (I
think) the toxicity of gluten in patients with coeliac disease, but be

> Any thanks is very appreciated.


Yours, Frank
Die Verwendung von mehreren Ausrufezeichen macht die Aussage nicht
ausrufender sondern ausufernder. [Michael Bauer in dnq]

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