Collagen is one of the most plentiful proteins present in the bodies of mammals, including humans. In fact, it makes up about 25 percent of the total amount of proteins in the body. Some people refer to collagen as the glue that holds the body together. Without it, the body would, quite literally, fall apart. Collagen is a type of protein. Fibrous in nature, it connects and supports other bodily tissues, such as skin, bone, tendons, muscles, and cartilage. It also supports the internal organs and is even present in teeth. There are more than 25 types of collagens that naturally occur in the body. Possessing great tensile strength, it functions in a manner that is very different from many other types of proteins. For example, it can be found both inside and outside of cells. Collagen fibers are important in contributing to the external structure of cells. However, they are present on the inside of some cells as well.
Collagen works hand-in-hand with elastin in supporting the body’s tissues. Basically, it gives body tissues form and provides firmness and strength; elastin gives the same body tissues much need flexibility. This combination of collagen and elastin is very important in many parts of the body, including, but not limited to, the lungs, bones, and tendons. Even the blood vessels rely on both collagen and elastin. Often, collagen is discussed in relation to the skin. It works with keratin to provide the skin with strength, flexibility, and resilience. As people age, however, collagen degradation occurs, leading to wrinkles. As such, it is an important substance for those looking for ways to fight the visible effects of aging on the skin. Some skincare professionals actually advise people on ways to stimulate the production of collagen in skins cells.
Collagen is an inextensible fibrous protein that is found in connective tissue - bone, tendons, and skin. The objective of this exercise is to develop an understanding of the fibrous portion of collagen and to show how the different levels of protein structure come together and form a highly ordered and stable fiber. Three helicial peptides combine to form tropocollagen, and five tropocollagens combine to form a fiber segment. It is important to realize that in an actual fiber segment the ends of the tropocollagen would be staggered rather then flush-cut as shown in the model presented herein. The staggered ends would permit overlap in the association of the tropocollagens in adjacent segments, and thus aid in forming a strong fiber. Collagen's properties of rigidity and inextensibility are due to this highly ordered structure. The non-structurally order part of collagen is not illustrated in this model. This part of the protein complex having a different amino acid composition, lysine and hydroxylysine are particularly important residues, is globular in nature and not as structurally organized. Lysine and hydroxylysine form covalent crosslinks in the protein complex, thereby adding strength and some flexibility to the fiber.