What are proteins? Why are they important to us? Why would altering a protein's shape be important?Back to the genetics page
A protein is a molecule that consists of a chain of amino acids. There are 20 different amino acids to choose from, and the genetic information in our DNA determines how they're put together. A single protein consists of hundreds of amino acids, all folding into a structure with a specific shape.
What job a protein does in the body is determined by its structure (its conformation) and the way it moves (its dynamics). Hemoglobin, for example, is an important red blood cell protein that delivers oxygen to tissues and hauls carbon dioxide to the lungs for removal. In the lungs, oxygen binds to the iron atoms inside a hemoglobin molecule and any attached carbon dioxide is released.
In the tissues, the molecules of oxygen are released and more carbon dioxide is picked up. As illustrated in the video segment, it is the motions of parts of the hemoglobin molecule that makes this binding and release action work.
Scientists can investigate these motions or dynamics as well as the protein's structure using a technique called NMR (nuclear magnetic resonance) spectroscopy. The nuclei of some atoms are like little magnets; they align within a magnetic field. If disturbed by a very quick blast of radio waves, this alignment is disrupted and these little magnets gradually relax back into alignment with the field. Researchers can interpret this NMR relaxation to get very detailed information about molecular motion and how proteins do their many different tasks in the body.
1. A protein's structure and activity allow it to accomplish its function. How do you use your own shape and movement to accomplish tasks?
2. You need to eat protein to survive. What foods contain protein? Do you think you get enough protein in what you eat? How can you find out?
* four 10" - 12" cardboard tubes (from plastic wrap or aluminum foil)
* four 30" - long pieces of Velcro (with peel-off sticky back)
* cotton balls
* Ping-Pong or golf ball
1. Each member of the group will make one helix: Hold one of the tubes vertically and wrap the Velcro strip around the tube in a spiral pattern. Attach the cotton balls to the Velcro an inch apart from each other. Can you see how this resembles a helix structure of a protein? What do the cotton balls represent?
2. Position four tubes together so that the cotton balls of one tube touch the Velcro strip of another. They should be able to hold together this way. What happens if you combine yours with another group's?
3. Now take the Ping-Pong or golf ball and try to get it into the middle of your four helices. What do you have to do to get it to fit inside? How is this similar to what a protein does to accommodate a smaller molecule? What kinds of molecules change their conformation like this to do their job?
Why is it important for researchers to know the shapes of different proteins? How do you think they are able to alter a protein's shape?
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