Proteins and Misfolds

Author: William Tsay

Editors: Ken Saito and Peggy Yang

Artists: Tiffany Chen

You may have heard that humans need proteins to survive. Yes, they are indeed an important part of your body. In fact, proteins are one of the most abundant organic molecules in living creatures and have the most diverse range of functions. But how can even the tiniest alteration in its structure cause death?

Proteins are among one of the four biological macromolecules, lipids, carbohydrates, and nucleic acids. They are large, complex molecules that act as enzymes, messengers, antibodies, and performing courier and structural roles. Proteins are synthesized during a process of transcription and translation. DNA, or deoxyribonucleic acid, is the genetic blueprint of cells in an organism’s body. It codes for smaller amino acids or peptides, which are building blocks for proteins. When hundreds and thousands of peptides bond together, they form a polypeptide which in this case, is protein.

The shape of a polypeptide is what makes each one unique. Each of the 22 amino acids are configured differently which leads to different outcomes. The amino acid sequence determines the shape of the protein, and the shape determines the function; therefore, if the shape were to be altered, the protein will not be able to perform its function. The alteration of a protein’s shape is called denaturation. Factors that can change its shape include temperature, pH, and salinity (salt concentration). Furthermore, most proteins have an optimal environment—the environment in which they perform the best. For example, pepsin, an enzyme in the stomach that helps break down food, has an optimal pH of two, a relatively acidic environment. If pepsin was exposed to a ph of 11, it would denature from the drastic difference in living conditions. When a protein becomes denatured, its internal bonds break and unfold causing it to lose its function.

Usually, a misfolded protein will be disposed of by the PQC (protein quality control) system. Overloading of this system will cause an accumulation of misfolded protein, which can be a result of numerous diseases. Scientists believe this to be the primary cause of many detrimental diseases including cystic fibrosis, Alzheimer’s disease, Parkinson’s disease, and Huntington's disease. This proves the essentiality of proteins and their crucial role in our bodies.

Citation:

Rye, Connie, et al. “2.3 Biological Molecules.” Concepts of Biology 1st Canadian Edition,

BCcampus, 14 May 2015,

opentextbc.ca/biology/chapter/2-3-biological-molecules/.

S;, Chaudhuri TK;Paul. “Protein-Misfolding Diseases and Chaperone-Based Therapeutic

Approaches.” The FEBS Journal, U.S. National Library of Medicine,

pubmed.ncbi.nlm.nih.gov/16689923/#:~:text=Protein%20misfolding%20is%20believed%20to,other%20degenerative%20and%20neurodegenerative%20disorders.

JH;, Gregersen N;Bross P;Vang S;Christensen. “Protein Misfolding and Human Disease.”

Annual Review of Genomics and Human Genetics, U.S. National Library of Medicine, pubmed.ncbi.nlm.nih.gov/16722804/.

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