sequence's ends -- crucial to protein folding too?

Artem Evdokimov AEVDOKIMOZ at cinci.rr.com
Sat Sep 21 13:40:22 EST 2002


IIRC, it is turned around. What you say is essentially the same thing - you
take a portion of the protein and re-ligate it tail-to-nose. Topologically
equivalent to 'turning around' i think :)

As a result of this cleavage-religation, about 25% of all natural ConA is
cleaved - the two chains hang on together by noncovalent interactions :)
When you run Cona on an SDS you always see three lines, unless your ConA has
been specially purified to remove the cleaved portion. It's always a pain in
the ass when you refine the structure, because of that portion - it
co-crystallizes along with the uncleaved chains.

No one really figured out WHY conA is so abundant :) All the reasons I have
read did not satisfy the fact that there's about 3-8% of conA in the total
protein of the seeds.

> Is it turned around? I never had close look at the sequence or the
> strucutre. But in the legume lectin reviews I read (and I read a couple
> in the last months), they always say that it is circularly
> permuted. That would mean that there is no change in the structure, only
> the old termini are re-ligated and the new ones are free. The original
> termini are very close to each other in the legume lectin monomer
> (separated just by a "non-existing" beta-turn).

A.G.E.






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