Homework4 - hydrolyzes the di-amino acid Phe-Phe there is...

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Name David Chen Chem 4711, Homework 4 (Due 11/3 in class) Only use the space provided to answer the following questions. 1. Suppose that while you consumed your Wendy’s hamburger, you replaced the air in your digestive tract with H 2 . Assuming that you are not a smoker, how would this likely affect the ability of chymotrypsin to digest the protein in the hamburger and why? The polypeptide chains in chymotrypsin would no longer be interconnected by disulfide bonds. Therefore, the enzyme would stop digesting proteins. When air is replaced by H2, a reducing environment takes place which prevents formation of S-S bonds that connect the polypeptide chains in chymotrypsin. 2. How would you define a perfect enzyme physiologically? Every time enzyme meets its substrate, a reaction occurs. Kcat/Km of those enzymes is 10 8 to 10 9 3. When chymotrypsin hydrolyzes p-nitrophenolacetate, there is a burst of p-nitrolphenol released. When it
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Unformatted text preview: hydrolyzes the di-amino acid Phe-Phe, there is not a burst of phenylalanine released. Why? 4. In chymotrypsin, suppose you replaced the aspartate that is part of the catalytic triad with an asparagine. How would this affect the reaction and why? serine oxygen attacks the carbonyl carbon of a peptide bond, the hydrogen-bonded His functions as a general base to abstract the serine proton, and the negatively charged Asp stabilizes the positive charge that forms on the His residue. This prevents the development of a very unstable positive charge on the serine hydroxyl and increases its nucleophilicity Asp use proton shuttle to His which enhance the Ser’s nicelophilicity. 5. You want to know which of two substrates that an enzyme prefers. What kinetic parameter would you compare and why? Vmax/Km defines who much a enzyme likes substrate. Specificity constant...
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Homework4 - hydrolyzes the di-amino acid Phe-Phe there is...

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