Protein Structure Chains

Question

[alphaace]

Hi,

Can someone please explain how different protein chains occur exactly? I'm not talking about the side chain, but the protein chain which is typically labelled as A,B,C etc in the PDB. I'm curious as to how they are first found and what causes them? As far as I understand, the protein backbone could be in any of several conformations and each conformation has a label? Is that correct?

[Dunois]

You can "freeze" the backbone into (mostly) a single conformation (think crystallography, cryo-EM), and then image that.

Edit: derp, not sure why I commented on a post that's half a decade old.

Answer 1

[David Westergaard]

I'm not sure I understand you question, but I'll try to answer it as good as possible.

I assume you're refering to the secondary structure of a protein. As far as I know, only alpha helixes and beta sheets are listed on the PDB website (though other, less common ones, do exist.) Most structures in PDB are determined by either crystallography or NMR (some are computational models as well.) As to what causes them, that's biology 101, and I suggest you read the wiki page.