COLLAGEN STRUCTURE AND FUNCTION
Proteins are the most diverse class of biological molecules. Most of your body is made up of proteins. Each protein consists of one or more polypeptide chains, in which amino acids are strung together in a specific order. This amino acid sequence or 'primary structure' is the key to the shape and function of the protein. Interactions among different amino acids along the length of the polypeptide chain cause it to coil, bend, and fold into a complex shape. Some proteins consist of two or more polypeptide chains. In many cases, the polypeptide chains form a rounded or globular shape. Most enzymes are like this, as is the oxygen-carrying hemoglobin molecule. In other cases, polypeptide chains form long strands or sheets. These fibrous proteins are often structural components, such as keratin and collagen.
Activity
In this activity, you will explore the structure and function of collagen, the most abundant protein in the human body. You will begin by visiting a Protein Data Bank site, where the structure of collagen is described and illustrated in a "Molecule of the Month" feature. Next, you will research the effects of osteogenesis imperfecta (OI), a genetic disorder that affects the structure or number of collagen molecules.
Part 1.
Use your browser to go to http://www.rcsb.org. This site is a Protein Data Bank where you can search for any information about your favorite proteins, including everyone’s favorite, collagen.
Read the information and view the graphics. Use this information to answer the following questions:
1. Describe the primary structure of collagen. What are the major amino acid components in collagen?
The primary structure of collagen is a linear sequence of amino acids. To form polypeptides amino acids will combine.
2. What role does vitamin C play in collagen formation? What happens when a person does not get enough vitamin C in his or her diet?
-Hydroxyproline takes place after the collagen is built. The reaction needs vitamin C to help the addition of oxygen. Since we are able to get produce vitamin C in our bodies then we have to make sure we get enough in our diets. When we do not get enough vitamin C it will slow the production of collagen which can cause scurvy and its easier for you to bruise.
3. Describe the quaternary structure of collagen (the way in which the polypeptide chains are arranged).
The quaternary level of protein structure is the tropocollagen. A tropocollagen is made up of three polypeptide chains which wind together to form a triple helix.
Part 2.
Use your browser to go to the Web site of the Osteogenesis Imperfecta Foundation at
On the left side of the home page, click the link “About OI”, then find the “Facts About OI” section.
Read the material in the sections entitled "Facts on Osteogenesis Imperfecta” and “Types of OI.” Use what you have learned to answer the following questions:
1. What is the main symptom of osteogenesis imperfecta? What are some other symptoms that people with OI may have?
The main symptom of osteogenesis imperfecta is really fragile bones that break and fracture easily. Some other symptoms that people with OI may have is muscle weakness, fatigue, brittle teeth, curved bones and scoliosis.
2. Type I osteogenesis imperfecta causes fewer problems than the other forms. How does the collagen structure in Type I OI differ from that of the other types?
The collagen structure in Type I are mild fragility with few fractures and mild limb deformities.
Read the handout (pdf) in the resources section on Bone Structure.
1. Describe the role of collagen in bones. Why do collagen problems lead to bone problems?
The role that collagens plays in bones is similar to building a bridge. The steel rods are cased with cement, without the steel rods the cement would be brittle and fracture with small amounts of movement. Collagen is like the steel rods and the minerals in bones are like the cements. Your bones aren't as strong without collagen, they can fracture and break easily.
