A1. Threonine is an essential amino acid that is classified as slightly polar due to its hydroxyl group and the ability to easily donate a hydrogen atom. This as well makes it hydrophilic and often will saturate the outer region of a water soluble protein. They hydroxyl side chain can undergo glycosylation by adding saccharides and phosphorylation by adding phosphate through the actions of threonine kinase (New World Encyclopedia, 2015).
B. Protein Structure
C. Peptide bond through dehydration
D. Peptide bond broken through hydrolysis
E. Four forces that stabilize tertiary protein structure
The tertiary structure is the last shape formation that a protein undergoes and is determined by the various interactions that occur involving the variable R-group of each amino acid. This complex three-dimensional structure is stabilized by four forces: hydrogen bonding, hydrophobic bonding, ionic/hydrophilic bonding and disulfide bonding (Borges, 2014).
Hydrogen bonds occur between polar, or charged amino acids. Hydrophobic bonds avoid water and occur between nonpolar amino acids. Due to their hydrophobic nature, these bonds often occur in the center of the structure and help pull it tightly together. Both the hydrogen and hydrophobic bonds are fairly weak, with hydrogen being the stronger of the two. Ionic bonds also known as hydrophilic bonds occur between the two opposite charged R-groups. The strongest of the four bonds is the disulfide bridge that literally holds the structure together. This bond is a covalent bond between two sulfur atoms that occurs only between two cysteine amino acids (Borges, 2014). F. Bovine Spongiform Encephalopathy
Prions are types of proteins that do not require nucleotides to reproduces. In 1997, Stanley Prusiner discovered prions and theorized that they existed in two forms: cellular (PrPc); and infectious (PrPSc), and that the two forms were exactly the same in amino acid sequence but differed in the three-dimensional structure (Wiley, 2002).
Proper folding of proteins is supervised by special proteins called chaperones. The chaperones have the main role of ensuring proper folding. When a chaperone protein becomes toxic, major changes in the conformation occur as the alpha helix becomes beta pleated sheets. The sheets now expose the hydrophobic amino acid and aggregation, or clumping together of sheets occurs (Borges, 2014).
In bovine spongiform encephalopathy (BSE), the disease is caused by the misfolding of proteins that cause proteins and peptides to develop a fibrillary structure. The PrPc is a correctly folded prion and the misfolded form is called PrPSc. BSE occurs when the normal PrPc come into contact with the toxic PrPSc and the normal prion takes on the shape of the PrPSc. The normal chaperones are unable to convert the PrPSc back to the normal form. The PrPSc now takes on the role of chaperone and the conversion of PrPc prions continue over and over. PrPSc, now being hydrophobic avoids the water of the inner cell and begin to accumulate and form plaques along the neuronal cell membranes. The aggregation of the prions on the cell membrane eventually lead to cell death which produces the sponge-like appearance in the brain of cattle infected with BSE (Thompson, 2014). F4. Recommendations in decreasing the risk of BSE
BSE is a form of transmissible spongiform encephalopathy that is transmitted when cattle consume feed that contains other animal protein from infected animals such as scrapie in sheep (CDC, 2010).
As countries are beginning to develop regulations to help eradicate BSE, instances of infected cattle are decreasing (CDC, 2010). For areas who have not yet established regulations, some recommendations for them to consider would be to omit any animal tissue that could potentially be infected from being used in animal feed and fertilizer. The ban should include not only livestock feed, but pet food as well. Cattle are grazing animals and could potentially come in contact with and ingest pet food or fertilized foliage that has been contaminated. It is known that humans who consume beef contaminated with the toxic prions that cause BSE can develop the human form of TSE (Helmenstine, n.d.).
A simple education program for the public should be implemented warning that cooking will not destroy TSE prions; therefore, education should also include the risks associated with eating any beef that could be infected as well as eating processed meats such as hot dogs, ground products, bologna and lunch meats of an unknown source (Helmenstine, n.d.). The final recommendation would be to euthanize any cattle that exhibit symptoms of BSE and cremate the remains so that the carcass cannot be eaten by any other animal and hopefully will prevent transmission.
Borges, K. (2014). Protein Structure. Video. Retrieved from http://wgu.hosted.panopto.com/Panopto/Pages/Viewer.aspx?id=b8686074-1a41-428c-ab18-037fa5e070e3 Boundless. (2014). Boundless Biology: Protein Structure. Image. Retrieved on March 19, 2015 from https://www.boundless.com/biology/textbooks/boundless-biology-textbook/biological-macromolecules-3/proteins-56/protein-structure-304-11437 CDC. (2010). Centers for Disease Control and Prevention: BSE (Bovine Spongiform Encephalopathy, or Mad Cow Disease. Retrieved on March 19, 2015 from http://www.cdd.gov/ncidod/dvrd/bse/ Helmenstine, A. (n.d.). Mad Cow Disease: What You Need to Know About Bovine Spongiform Encephalopathy. Chemistry About.com. Retrieved on March 19, 2015 from http://chemistry.about.com/cs/howthingswork/a/aa122703a.htm New World Encyclopedia. (2015). Threonine. Retrieved on March 20, 2015 from http://www.newworldencyclopedia.org/entry/Threonine Purdue University Department of Chemistry. (n.d.). Image. Retrieved on March 20, 2015 from http://www.chempurdue.edu/gchelp/molecules/thr.gif Steade, R. (n.d.). Bioptics.co.uk: Hydrolysis of a dipeptide. Image. Retrieved on March 20, 2015 from http://www.biotopics.co.uk/as/dipeptidehydrolysis.html Thompson,