. The allosterically regulated enzyme ATCase binds aspartic acid as asubstrate and acylates the a-amino group. Succinate acts as a competitiveinhibitor of ATCase because it binds the active site but can't be acylated. Thedependence of vo on [aspartic acid] for ATCase is shown in panel (a) of theaccompanying figure. Panel (b) shows the effect of increasing [succinate]on v, when [Asp] is held at a low concentration (see thick vertical arrow inpanel (a)). Note that in panel (b), vo is not zero when [succinate] =0 (seethin horizontal arrow). Explain the shape of the curve in panel (b). Whydoes v, increase initially, before decreasing at higher [succinate]?Co0-COOCH2CH,HC -NH,CH,COOCOOAspSuccinate[Asp)[Succinate][Asp] inexperiment b(a)(b)

The allosterically regulated enzyme ATCase binds aspartic acid as a substrate and acylates the…

Answered: . The allosterically regulated enzyme…

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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In enzyme catalysed reactions, the energy level of the enzyme/substrate (or ES) complex is higher (or raised) compared to the uncatalyzed reaction. List 4 factors that contribute to this raised energy level and explain how each of these factors contribute to the higher energy level of the ES complex
cis-Vaccenate is an 18-carbon unsaturated fatty acid abundant in E. coli membrane lipids. Propose a metabolic route for synthesis of this fatty acid, in light of the fact that stearic acid, the C18 saturated analogous fatty acid, is virtually absent from E. coli lipids.
ATP is a (+) allosteric effector, and CTP is a (-) allosteric effector of theenzyme ATCase. Both of these heterotropic effectors bind to the regulatorysubunits on ATCase. The substrates of ATCase, aspartate and carbamoylphosphate, bind the enzyme active site with positive cooperativity (i.e.,they exert a “+” homotropic effect on activity). As the concentrations ofthe substrates change from values where [S] ≪ KM to values where [S] issaturating ([S]≫ KM), how will the binding constants for each of the twoallosteric effectors change? In other words, does ATP bind ATCase withhigher affinity when [S] is low or high? Does CTP bind ATCase with higheraffinity when [S] is low or high?
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
Changing which pairs of the amino acids is most likely to directly lead to the most severe problems with substrate (Blue) binding by the protein depicted by the red ribbon.
In bacteria, isocitrate dehydrogenase is regulated by phosphorylation of a specific Ser residue in the enzyme active site. X-ray structures of the phosphorylated and the nonphosphorylated enzyme show no significant conformational differences. How does phosphorylation regulate isocitrate dehydrogenase activity? O The phosphoryl group sterically hinders the substrate. O The phosphorylation bears a negative charge, which repels the substrate. O The phosphoryl group attracts positively charged Ca2* cations, which block the active site on the enzyme. None of the above.
An enzyme that follows the MWC (concerted) model for allostery has a T/R ratio of 300 in the absence of substrate. Suppose that a mutation were to reverse that ratio (T/R = 1/300 = 3.3 x 10–3 in the absence of any substrate). How would this mutation affect the relation between the rate of the reaction and substrate concentration, i.e., what would a Vo vs. [S] plot look like, and why?
make a schematic diagram of BChE/AChE inhibitory determination Butyrylthiocholine iodide (BChI), as well as acetylthiocholine iodide(AChI) molecules were utilized as substrate compounds of the reaction. Inthis regard, 5,5′‐dithio‐bis(2‐nitro‐benzoic acid) compound (DTNB) wasused to estimate BChE/AChE activity. In summary, 100 μL Tris buffersolution (HCl, 1.0M, pH 8.0, Tris) and variety of concentrations of thesample solution (50‐200 mL) were added in deionized water and also20 μL of BChE/AChE enzymes solutions added. The mixture was thenincubated for 10 minutes at 20°C. Finally, 50 μL of DTNB (0.5 mM and25 mL) BChI/AChI were added to the incubator mixture. The reactionwas also started by adding 50 μL BChI/AChI. The activity of theseenzymes was evaluated using spectrophotometric spectra with awavelength of 412 nm.
Neuraminidase (NA) catalyzes a hydrolysis of the glycosidic linkages of sialic acids using a mechanism shown in Fig. (a). and Fig. (b) shows competitive inhibitors of NA Considering the mechanism of NA, why do zanamivir and oseltamivir inhibit NA so potently?
Amino acid alanine
Based on your understanding of the structure and function of the enzyme chymotrypsin, explain why proteolytic activation by Trypsin in the intestine is required for chymotrypsin to bind its substrates with high affinity. Your answer should include a description of the amino acid residue or residues involved AND a kinetic experiment that suggested this.

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