Diisopropylphosphofluoridate (DIPF) inactivates chymotrypsin by covalently modifying serine 195.Which statement is true of DIPF's inhibitory mechanism?DIPF randomly modifies all serine residues on the protein, and if enough is added, the serine in the active site willeventually be modified.DIPF approaches serine 195 more closely than other substrates.DIPF looks like the substrate for chymotrypsin and binds in the active site as a competitive inhibitor.Serine 195 is in an environment that gives it a higher than normal reactivity with respect to DIPF.

Diisopropylphosphofluoridate (DIPF) is an irreversible inhibitor of chymotrypsin. It forms a…

Answered: Diisopropylphosphofluoridate (DIPF)…

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 isolated a new protease that cleaves peptide bonds on the carboxyl side of Asp and Glu. Based on the enzyme's inactivation by DIPF, you suspect that it may utilize a mechanism similar to chymotrypsin. The difference in specificity might be explained by the absence of the S1 binding pocket. replacement of serine 195 with a positively charged residue. presence of a positively charged residue in the S1 binding pocket. presence of a negatively charged residue in the S1 binding pocket.
An active site of a hypothetical serine protease with a peptide substrate bound is shown below: This serine protease has 3 specificity pockets (S1, S2, S1') as shown in the figure above. S1 pocket has a glutamic acid in the bottom, the S2 pocket is small and hydrophobic, and the S1' pocket is deep and hydrophobic. Based on this information you can conclude that R1 is most likely side chain of a. Asp b. Lys c. Lle d. Gly e. Phe
TLCK and TPCK both use Histadine residues in the active site as inhibitors of serine proteases. Why is TLCK specific for trypsin and TPCK is specific for chymotrypsin?
Why Phenylmethylsulfonyl fluoride (PMSF, shown in Fig.) does not inhibit aspartate protease as potent as serine protease?
Using the catalytic mechanism of serine proteases, draw and label a reaction coordinate diagram/graph of the chymotrypsin-catalyzed hydrolysis of a peptide bond.
Phosphoglycerate kinase shows induced fit resulting from the binding of both substrates to form the closed catalytic conformation. Maintainence of the closed conformation depends on the formation of a salt bridge between R62 and D200. What would be the effect of the mutation of D200 to the unusual amino acid shown below? Explain.
Trypsin uses a nearly identical mechanism as chymotrypsin (including the catalytic triad his57-ser195-asp102. beginning with the enzyme substrate complex draw the complete steps in the trypsin mechanism that occur to release the first product and create the acyl enzyme intermediate in the trypsin active site. The substrate for trypsin to be used is gly-lys-gly-ala
The allosterically regulated enzyme ATCase binds aspartic acid as a substrate and acylates the α–amino group. Succinate acts as a competitiveinhibitor of ATCase because it binds the active site but can’t be acylated.The dependence of v0 on [aspartic acid] for ATCase is shown in panel (a)of the accompanying figure. Panel (b) shows the effect of increasing [succinate] on v0 when [Asp] is held at a low concentration (see thick vertical arrow in panel (a)). Note that in panel (b), v0 is not zero when [succinate] = 0 (see thin horizontal arrow). Explain the shape of the curve in panel (b). Why does v0 increase initially, before decreasing at higher [succinate]?
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
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
Which of the following statements are descriptions of metal ion catalysis or examples of metal ion catalysis? Choose all correct answers a Zn²+ cofactor may properly orient the substrate in the active site through ionic interactions. a covalent bond forms between enzyme and substrate lowers the energy or stabilizes the transition state or intermediate catalyst retains its original form after reaction occurs catalysts may participate in oxidation-reduction reactions by changes in the oxidation state

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