Proteins and Enzymes

ID #1027

I think Im just misinterpreting information, or possibly over thinking the structures of proteins- nevertheless, from the readings in the book I got the idea that for a protein to function in a certain way it had to go through all four folding stages (i.e. the way a protein is folded determines what it does). However, in lecture on friday, we talked about how many proteins stop at various levels of structures. If that is the case, then what do proteins do at the primary structure or secondary structure?

Every protein has its own primary structure -- this is just the sequence of amino acids from N-terminus to C-terminus. Most proteins will have one or more regions of secondary structure -- that's alpha helix and/or beta sheet. All polypeptide chains will have a final 3-dimensional structure, which includes interactions of regions of secondary structure with each other and with regions of the protein that didn't adopt any secondary structure. If the polypeptide chain is a functional protein all by itself, then tertiary structure is as far as it goes. But in the cell, many if not most functional proteins are multimeric, meaning they have multiple subunits. The final 3-dimensional shape of the finished protein including the association of all its subunits is then called quaternary structure. Please spend some time with the figures I got from your Purves text and used in class -- they do a better job of describing this than I do.

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