Protein Folding Question From a Non-Scientist

[Alan C. Lawhon]

Today I was attempting to explain protein folding (and misfolding) to a potential new folder. I pointed to this Wikipedia graphic:

http://en.wikipedia.org/wiki/File:Protein_folding.png

and explained how a fold initially starts as a string of amino acids where atoms "bond" and the chain goes through a "twisting process" that eventually results in the molecule reaching its final stable three dimensional shape. I felt that this particular graphic is a good visual representation of that process.

I got to thinking about this and noticed that in this particular graphic there is only a single chain (or amino acid string) at the beginning of the fold. So I'm wondering: Do all protein molecules start off as a single amino acid chain or do some proteins result from the folding (and bonding) of two or more amino acid chains?

[Jesse_V]

Well, the ribosome manufacturers the amino acid chain. These chains can form together to form more complex molecules such as large proteins. See http://answers.yahoo.com/question/index ... 848AATT73V and do a search for "protein" in http://en.wikipedia.org/wiki/Peptide_bond.

Proteins have several different structures to them. To take snippets from the Wikipedia article on "protein":

• Primary structure: the amino acid sequence.
• Secondary structure: regularly repeating local structures in the amino acid chain, such as alpha helixes and beta sheets.
• Tertiary structure: the overall shape of a single protein molecule; the spatial relationship of the secondary structures to one another. The term "tertiary structure" is often used as synonymous with the term fold. The tertiary structure is what controls the basic function of the protein.
• Quaternary structure: the structure formed by several protein molecules (polypeptide chains), usually called protein subunits in this context, which function as a single protein complex.

So yes, proteins can result from multiple amino acid chains connecting together. The ribosome itself consists of a bunch of proteins and other molecules. But as for if the proteins fold and then connect, or connect and then fold, or fold together or separately at the same time, I don't know.

[Alan C. Lawhon]

Jesse:

I found this interesting video of protein structure on YouTube. (After watching this, I understand what is meant by the term polypeptide chain.)

http://www.youtube.com/watch?v=lNh0Km4b ... =endscreen

Man, how can you stand living up there in ice box Alaska?

[Jesse_V]

Man, how can you stand living up there in ice box Alaska?

Idk, I mean I have to type these forum posts quickly because the cold tanks my laptop's battery life, but actually living in an igloo has its upsides.