Bio Unit 2.2 Discussion

Bio Unit 2.2 Discussion - (1). Please discuss how proteins...

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(1). Please discuss how proteins can fold rapidly and reliably to their native conformation and how misfolded proteins can lead to diseases. I would like to note that this discussion is guided largely by information provided in our textbook, Life: The Science of Biology , which provides an excellent overview on the fundamental concepts related to proteins. To begin, let’s do a short review. First, we know that proteins are macromolecules. The building blocks of proteins are monomers called amino acids. Covalent bonds called peptide bonds link amino acids together through condensation reactions to form polypeptide chains, which are essentially proteins. Protein structure can take 4 forms: 1.) Primary structure, which is basically just the sequence of amino acids; 2.) Secondary structure, in which hydrogen bonds between the C= O and N— H molecules cause the polypeptide to twist into alpha helices or fold into beta pleated sheets; 3.) Tertiary structure, in which the polypeptide chain becomes compacted, typically in aqueous environments, such that nonpolar side chain groups of amino acids face inward and polar side chain groups of amino acids face outward; 4.) Quaternary structure, where various kinds of noncovalent bonds (e.g., van der Waals interactions, hydrophobic interactions, ionic bonds, and hydrogen bonds) hold polypeptides (designated as subunits) together to form a structure. We can conclude by this review that there are numerous different forces that play a role in producing the overall structure of a protein. From that discussion, we must then wonder what determines the kind of interactions that occur within and between polypeptide chains? The key is the amino acid sequence. We know of this fact primarily based on the work of Christian Anfinsen of the 1950s ({{138 Anfinsen,Christian B. 1973; }}). In his study, Anfinsen used chemicals such as urea or guanidinium chloride to disrupt the noncovalent bonds that held together an enzyme called ribonuclease. The chemicals successfully uncoiled, or denatured, the protein into its polypeptide chain, which removed its ability to function normally as an enzyme. However, when he removed the ribonuclease from the urea, the polypeptide chain slowly
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This note was uploaded on 04/10/2011 for the course AAS 410.303.81 taught by Professor Pan during the Spring '11 term at Johns Hopkins.

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Bio Unit 2.2 Discussion - (1). Please discuss how proteins...

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