3 In many cases, the wrong residue at the active sitefunctional protein. Which of the following residues could be inserted in place of Ser-195 in chymotrypsin and have the least negative impact on the enzyme's catalyticability?a protein will result in a non-A) GlycineB) IsoleucineC) TyrosineD) GlutamateE) MethionineQuestion 13Which of the following R-groups would remain in ionized form (i.e., protonated) atpH = 12.00?A) ArginineB) HistidineC) MethionineD) LysineO E) Cysteine

Most of the enzymes are proteins. The enzymes have an active site to which the substrate molecule…

Answered: In many cases, the wrong residue at the…

Biochemistry

9th Edition

ISBN:9781319114671

Author:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Publisher:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Chapter1: Biochemistry: An Evolving Science

Section: Chapter Questions

Problem 1P

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You have discovered a new enzyme that has a nearly identical active site to chymotrypsin. This new enzyme uses the same catalytic triad and the same reaction mechanism as chymotrypsin. Your new enzyme differs from chymotrypsin because it cuts peptides at the C terminus of polar, non- ionizable R groups.A) Beginning with the first tetrahedral intermediate, draw the mechanism of catalysis that occurs to cleave the tripeptide Asn- Phe- Lys substrate ending your answer with the product and free enzyme.
You have discovered a new enzyme that has a nearly identical active site to chymotrypsin. This new enzyme uses the same catalytic triad and the same reaction mechanism as chymotrypsin. Your new enzyme differs from chymotrypsin because it cuts peptides at the C terminus of polar, non- ionizable R groups. A) Beginning with the first tetrahedral intermediate, draw the mechanism of catalysis that occurs to cleave the tripeptide Asn- Phe- Lys substrate ending your answer with the product and free enzyme. B) From the list below, which of the components would most likely be found in the area of the enzyme that substitutes the hydrophobic pocket of chymotrypsin? Very briefly explain your choice(s): Ser ile Zn+ Val C) You've constructed a molecule that is able to bind to the 1st tetrahedral intermediate of your new enzyme, preventing catalysis. From experimental results, you can see that this molecule is only able to bind to the tetrahedral intermediate. Assuming that this enzyme follows…
Chymotrypsin, trypsin, and elastase all share the same catalytic mechanism, but have different specificities. (a) These proteases are considered serine proteases because the active sites contain serine, histidine and aspartate. Describe the roles that each of these amino acid residues play in hydrolyzing protein substrates. (b) The active site pockets of chymotrypsin, trypsin, and elastase are shown in the image below. Based on the image, which side chain of the amino acids would they prefer to cleave respectively, Ala, Arg, or Trp? Explain your answers. Val 216KVal 190 Asp 189 Chymotrypsin Trypsin Elastase
Chymotrypsin, trypsin, and elastase all share the same catalytic mechanism, but have different specificities. (a) These proteases are considered serine proteases because the active sites contain serine, histidine and aspartate. Describe the roles that each of these amino acid residues play in hydrolyzing protein substrates. (b) The active site pockets of chymotrypsin, trypsin, and elastase are shown in the image below. Based on the image, which side chain of the amino acids would they prefer to cleave respectively, Ala, Arg, or Trp? Explain your answers. Val 216 Val 190 Asp 189 Chymotrypsin Trypsin Elastase
You have discovered a new enzyme that has a nearly identical active site to chymotrypsin. This enzyme uses the same catalytic triade and the same reaction mechanism as chymotrypsin. New enzyme differs from chymotrypsin because it cuts peptides at the C terminus of polar, non-ionizable R groups. 1) Beginning with the first tetrahedral intermediate, draw the mechanism of catalysis that occurs to cleave the tripeptide Asn - Phe - Lys substrate, ending the answer with product x free enzyme.
What are the amino acids of the catalytic triad of chymotrypsin? State the mode of catalysis shown by each of the amino acids that you have named. (a) (b) Predict what will happen if aspartic acid of the triad is replaced by asparagine. (c) Briefly explain the role of the oxyanion hole for the catalysis of chymotrypsin.
mTOR is a cytoplasmic kinase that regulates cell division. Its misregulation can lead to cancer. The canonical mTOR inhibitor, rapamycin, is FDA approved as a cancer treatment. Rapamycin is an allosteric inhibitor that does not bind anywhere near the substrate binding site of the enzyme. A) What is the name of this type of inhibition? B) Sketch a REPRESENTATIVE double-reciprocal/Lineweaver-Burke plot that includes the enzyme kinetics for BOTH the uninhibited and inhibited reaction. Be sure to: 1) Make ABSOLUTELY clear which curve is your uninhibited reaction and which is your inhibited reaction. 2) Label the X and Y axes. 3) Indicate what the X- and Y-intercepts represent with regards to Michaelis-Menten kinetics. C) Can increasing the substrate concentration overcome this type of inhibition? Explain in a sentence or two.
How would chymotrypsin's catalytic triad be affected by extremely low and extremely high pH values (assuming the rest of the protein remains intact)?
An enzyme with an unknown reaction mechanism has been isolated and is being investigated in the lab. Based on the information given below, propose one or more specific catalytic strategies (covalent, acid-base, and/or metal ion catalysis) used by the enzyme and predict the role of each catalytic residue in the enzyme's reaction cycle. Explain your reasoning. (a) Mapping of the active site with substrate analog showed that it contains a critical Ser residue. (b) Studies conducted in buffers of varying pH showed that the enzyme is sensitive to pH changes and has two catalytically important residues with pKa values of ~10.5 and ~4.0. (c) Substitution of the Ser residue with Ala resulted in a five-fold increase in the KM but had no effect on the kcat. (d) The reaction rate was insensitive to the addition of metal chelators such as EDTA and EGTA.
Serine Proteases, such as chymotrypsin, contain Ser/Asp/His as a catalytic triad (i.e. three collaborating amino acids) of amino acids involved in enzyme catalysis. Why is this? Examine each amino acid of this catalytic triad (schematically detailed below: Ser195/Asp102/His57) and, based on your understanding of amino acid characteristics, predict what the role of each amino acid could be. His57 Ser195 Asp102
Consider the enzyme-catalyzed conversion of a substrate S into a product in the presence of an inhibitor I with the following properties (mixed inhibition): (i) The inhibitor competes with S to bind the active site of the enzyme with dissoci- ation constant K¡ for the complex (EI). (ii) The inhibitor is also capable of binding the enzyme at a secondary site of the enzyme with dissociation constant K{ for the complex (IES). The complex (IES) is unable to form P. iii) The dissociation constants of the (IES) and (EI) complexes satisfy the relation K{ = K1/2. What is the value of the ratio vo/(k2 [E]o) when the concentration of the substrate is [S]o = KM/3 and the concentration of the inhibitor is [I]o = K{/4? Recall that KM is the Michaelis constant.
UDP-glucuronosyltransferase enzymes bind the organic compound UDP-glucuronic acid (UDP-GA) in order to catalyse the transfer of a glucuronic acid group from UDP-GA to a drug molecule, releasing UDP from the active site as a product. UDP is then regenerated by the activity of another enzyme. What terms could be used to describe UDP-GA?

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