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Wednesday, January 09, 2008

The shape of structural proteins Fibrous

049. The structural proteins are involved in maintaining the shape of a cell or in the formation of matrices in the body. The shape of these proteins is:

1. Globular

2. Fibrous

3. Stretch of beads

4. Planar

Answer

2. Fibrous

Reference:

Harper 26th Edition Page 38

Lippincott 3rd Edition Page 43

Chaterjee 6th Edition Page 79

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Discussion

When the axial ratio of length: width of a protein molecule is more than 10, it is called a fibrous protein. Examples are alpha keratin from hair and collagen

When axial ratio of length: width of a protein molecule is less than 10, it is called a globular protein. Examples are Myoglobin, hemoglobin, Ribonuclease etc

Explanation

Collagen is the most abundant of fibrous proteins that constitute more than 25% of the protein mass in the human body. Other prominent fibrous proteins include keratin and myosin. These proteins represent a primary source of structural strength for cells (ie the cytoskeleton) and tissues.

Comments

There can be some confusion as to whether the shape of the collagen in “planar” due to the pleated structure we often talk about. But many books (including Gray’s Anatomy) just give the shape as fibrous and there is no mention of planar structure of structural proteins in standard books

Tips

In the early 1990’s, premier cell biologist Olga Marko began investigating the use of technology for stimulating a patient’s own cells to produce collagen. Research of this nature was then not yet regulated by the FDA. Through her research, Ms. Marko developed a process of extracting a patient’s own collagen-producing cells (dermal fibroblasts), growing and expanding those cells in a controlled environment, and then re-introducing the fibroblasts by injection into the skin of the patient’s face. Once injected, it was believed that the fibroblasts produced collagen which might prove to be beneficial in the repair of dermal defects. This research lead to the development of the Isolagen Process (ACS - Autologous Cellular System). At this time, the ACS process could be legally marketed.

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