If They Want To Make Anything, Proteins Must Know How To Fold
Originally published on Wed September 3, 2014 3:26 pm
MELISSA BLOCK, HOST:
Events unfold. Plots unfold. And this summer, NPR science correspondent Joe Palca has been telling us how science unfolds. It's series we're creatively calling Unfolding Science.
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BLOCK: Today, Joe tells us about large biological molecules called proteins that have to fold and unfold properly to keep us alive.
JOE PALCA, BYLINE: When we talk about food, protein is a kind of nutrient you get in meat, fish or foul. When we talk about cells in our bodies, proteins are large molecules that do all the things that are necessary for life. Things like recognizing invading microbes or turning food into energy or picking up the garbage inside cells. Vijay Pande studies these proteins. He's at Stanford University. He says, proteins are made of strings of smaller chemical components called amino acids.
VIJAY PANDE: What's amazing is that a typical protein might have 200, 300 of these pieces - of these amino acids that have to assemble themselves into a well-defined shape.
PALCA: The assembly process is called protein folding. How it happens is incredibly complex. The final shape depends on the physical and chemical properties of the amino acids that make up a particular protein. And the shape is critical at best. A misfolded protein won't be able to do it supposed to do. But Pande says, something worse happens in diseases like Parkinson's or Alzheimer's.
PANDE: In those diseases, what's believed to happen is that instead of the protein folding or assembling correctly to carry out its function, they misfold into some shape that actually is toxic.
PALCA: Now assuming everything works right, and the protein folds of the weight supposed to and finishes the job it's supposed to do, what you think happens then? It unfolds.
PANDE: Unfolding is a central part of nature.
PALCA: Once a protein has completed its work, it needs to be disposed of. So it gets a chemical tag that basically says, it's time to unfold.
PANDE: Because when it gets unfolded, other proteins can combine and chop them up.
PALCA: In the cool thing is that when the chopping up is done, all that's left is the amino acids that made up the proteins in the first place. And those same amino acids can be used to take a totally different protein - recycling at its finest. And there you have the unfolding science of protein folding. Joe Palca, NPR News. Transcript provided by NPR, Copyright NPR.