serine proteases act via a two-step catalytic mechanism. However, as a criticalscientist, you may want to see data that supports this claim. One experiment that can provide suchevidence is called a 'pre-steady state' kinetics experiment using the chromogenic substrate, N-acetyl-phenylalanine p-nitrophenyl ester.As shown below when this substrate is cleaved, the p-nitrophenylate is a yellow product whoseabsorbance can be measured in real time using a spectrophotometer. When the chromogenicsubstrate is rapidly mixed together with a limiting amount of protease enzyme, the accumulation ofproduct is measured right away on fast (millisecond) timescales. In this experiment, one observes twodistinct phases of the reaction as shown in the plot below. Based upon what you know about themechanism of serine proteases, provide a mechanistic interpretation for the observation of these twophases of the reaction.+ H₂ON-Acetyl-L-phenylalanine p-nitrophenyl esterp-NitrophenolateAbsorbance(p.nitrophenolate releasedmilliseconds aftermixing

Serine proteases are protein cleaving enzymes that have Serine, Histidine and Aspartate (the…

Answered: serine proteases act via a two-step…

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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The purified OXA-M290 enzyme can now be tested to determine which β-lactamase inhibitor is most effective. This inhibitor could be prescribed in combination with a β-lactam antibiotic to treat the infection caused by the E. coli KGH1 strain. Before testing inhibitors against OXA-M290, the kinetic activity of this enzyme must first be measured. The activity of OXA-M290 is measured using nitrocefin, a chromogenic β-lactam antibiotic. When nitrocefin is hydrolyzed by a β-lactamase, it changes from yellow to red in colour. The nitrocefin hydrolysis product has an extinction coefficient of 20,500 M-1 cm-1 at 486 nm. The hydrolysis of 60 μM nitrocefin by 1 nM OXA-M290 is monitored using a microplate reader. The absorbance of the wells in the plate is measured at 486 nm every 30 seconds. This experiment is carried out with three replicates, generating the following data: Time (min) Absorbance of Replicate 1 Absorbance of Replicate 2 Absorbance of Replicate 3 0.5 0.0984…
The diagram below shows the substrate binding cleft for a protease, providing the substrate structure, and indicating the residues (using one-letter code) that line the four specificity pockets. 1 M F H₂N K R IZ 2 3 P F S W оо E 4 The protease is known to cleave the amide linkage between W and E residues for substrates containing the WEFD sequence. Using 3-letter code with amino acids linked by a "dash" (ex. GLY-ALA), the N-terminal product is A and the C-terminal product is A
The enzymatic activity of PFK1 is generally measured by set- ting up a coupled enzyme assay system whereby aldolase, triose phos- phate isomerase, and glycerol-3-phosphate dehydrogenase are added to the assay mixture. For the latter enzyme, NADH is added and its change in concentration is readily monitored at 340 nm. Write the chain of reactions catalyzed by these enzymes using structural formulas, label substrates and products, and explain why the coupled en- zyme assay system leads to oxidation of NADH. While the chain of reac- tions is similar to those in glycolysis, there is a critical difference because of the dehydrogenase enzyme. Describe how this enzyme causes the chain of reactions to differ from those in glycolysis.
There is total of 25 Enzymes and 27 Products that should be shown on this pathway
Since all of the B-lactams that you have tested are susceptible to hydrolysis by PAESBL-1, the hospital will not be able to use a single 8-lactam to combat this P. aeruginosa isolate. You need to consider alternative strategies. From the following list, select all of the strategies that might successfully overcome the broad substrate specificity PAESBL-1: Check all that apply. using multiple B-lactams simultaneously (e.g., rather than treating with amoxicillin alone, treat with the three B-lactams: amoxicillin, cephalothin, and imipenem). O using a reversible inhibitor of PAESBL-1 instead of a 8-lactam. Treat future infections by O combining a reversible inhibitor of PAESBL-1 with one or more 8-lactams. O using an irreversible inhibitor of PaESBL-1 instead of a B-lactam. O combining an irreversible inhibitor of PAESBL-1 with one or more -lactams. O O O O
The following complex natural product has been biogenetically produced via a pericyclic reaction(s) at the final stage. Can you propose the structure of the precursor? Но H. Me Me OH Me' rol Ме
Give a possible set of bacterial factors (or lack thereof) and what properties they have that would explain an increase in the 50% inhibitory concentration for tetracycline by 1,000-fold in an organism.
As stated in the text, mammalian cells can become resistant to the lethal action of methotrexate by the selective survival of cells con- taining increases in dihydrofolate reductase gene copy number so that intracellular levels of the enzyme become very high. What other biochemical or genetic changes in cells could cause them to become resistant to methotrexate?
In the pathway for degradation of BCAAs, which reaction takes place prior to the action of the BCKDC and what is the essential coenzyme for the reaction?
Two enzymes are being studied: the first enzyme E1, uses 2-tert-butyl-3- methylpentanopic acid as a substrate whereas the second enzyme E2, uses 2,3,4,5-tetraaminooctanoic acid as a substrate. Based on the lock-and-key model hypothesis, the active site of E, would be more * x with predominantly + x side chains and the active site of E2 would be more + x side chains
Sulfonamide drugs like sulfanilamide inhibit tetrahydrofolate biosynthesis. What intermediate or intermediates in purine synthesis would you expect to accumulate in sulfanilamide-treated bacteria? Suppose that a cultured mammalian cell line was treated with sulfanilamide. What intermediates might accumulate in these cells?

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