Concept explainers
Regulation of Glutamine Synthetase by Covalent Modification Suppose at certain specific metabolite concentrations in vivo the cyclic cascade regulating E. coli glutamine synthetase has reached a dynamic equilibrium where the average state of GS adenylylation is poised at
- increases,
- increases,
- increases,
- decreases.
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Biochemistry
- Make an electron-flow-mechanism for this synthetic scheme. This involves predicting major and by-products using electronic and structural effects. The arrow push mechanism must be shown.(from the reaction of α-ketoacids and oxaprolines to proteins that contain native serine residues ) with labelarrow_forwardUsing the ActiveModel for aldose reductase, describe the structure of the TIM barrel motif and the structure and location of the active site.arrow_forwardDistinguishing the Mechanisms of Class I and Class I Aldolases Fructose bisphosphate aldolase in animal muscle is a class 1 aldolase, which forms a Schiff base intermediate between substrate (for example. fructose-1, 6-bisphosphate or dihydroxyacetone phosphate) and a lysine at the active site (see Figure I8.12). The chemical evidence for this intermediate conies from studies with aldolase and the reducing agent sodium borohydride, NaBH4. Incubation of the enzyme with dihydroxyacetone phosphate and NaBH4 inactivates the enzyme. Interestingly, no inactivation is observed if NabH4 is added to the enzyme in the absence of substrate. Write a mechanism that explains these observations and provides evidence for the formation of a Schiff base intermediate in the aldolase reaction.arrow_forward
- Predict the effect of each of the following amino acid substitutions on the KM and kcat of the enzyme-catalyzed reactionsarrow_forwardThe Payoff Phase of Glycolysis in Skeletal Muscle In the skeletal muscle, in anaerobic conditions, glyceraldehyde 3- phosphate is converted into pyruvate during the payoff phase of glycolysis; and this pyruvate is reduced into lactate during lactic fermentation. 1-Write the 11 balanced biochemical equations corresponding to all| the reaction steps leading to the conversion of glyceraldehyde-3- phosphate into lactate through glycolysis followed by lactic fermentation. 2-Write the net equation of the whole transformation process (i.e. with glyceraldehyde-3-phosphate as the starting substrate; and lactate as the end product).arrow_forward7.arrow_forward
- protease mechanism: you isolate a new protease which cleaves the peptide bond 2 aa residues before a F residue. You might expect to fınd... O An I residue in the S2'pocket AL residue in the S2 pocket O aV residue in the oxyanion hole An Lresidue in the catalytic triad in Michaelis-Menton kinetics, cutting the enzyme concentration in half will O will double the reaction rate O will not change Vo and Vmax will change Vo but not turnover number decrease Km by halfarrow_forwardGlucosidase I catalyzes hydrolysis of specific glucosidase I is a synthetic trisaccharide, glucose-al-2- glucose-al-3-glucose-a-O(CH₂) #COOCH3. Kinetic measurements oligosaccharides containing glucose. obtained using this trisaccharide as substrate in the deoxynorjirimycin at concentrations of 50 μM (), 100 μM absence (x-x) and presence of the inhibitor 1- A) were used to prepare the (-), and 200 μM (4 Lineweaver-Burk plot below: b) Page 3 12) 7. a) V/V (nmol/hr)-1 1.S 1.0- 0.5 1/Trisaccharide (mM)-! Estimate the values for Vmax and KM for the trisaccharide substrate in the absence of the inhibitor. 0.0 -1.0 0.0 One substrate for 1.0 2.0 Determine whether inhibition by 1-deoxynorjirimycin is competitive, non-competitive or neither.arrow_forwardApproximately how much does staphylococcal nuclease (Table) decrease the activation free energy ΔG‡ of its reaction (the hydrolysis of a phosphodiester bond) at 25°C?arrow_forward
- 6-25 substrate-band enzyme concentrations. The the turnover number is equal to umax- b) V=Umax •57(Km+S) anstont For an enzyme that displays Michaelis-Menten kinetics, what is the reaction velocity, V (as a percentage of Vmax), observed at the following values? a) [S] = KM C) d) e) [S] = 0.5KM [S] = = 0.1KM [S] = 2KM [S] = 10KM w reactores -maximumrate of reaction boteles conc. Would you expect the structure of a competitive inhibitor of a given enzyme to be similar to that of its substrate?arrow_forwardPuting a metabolic pathway map together which includes glycolysis, gluconeogenesis, glycogen synthesis & glycogenolysis, and the two types of fermentation, and pyruvate oxidation (to acetyl-CoA). The map should have/illustrate/show all of the indicated 6 pathways stated previously on the same page, to emphasize how these processes are related to each other. map should include: a) Clear labels for all the pathways b) All the pathways shown on the same page and correctly integrated with each other, i.e., it should be clear which reactions are shared by different pathways c) The names of all metabolites (common abbreviations may be used) d) The names of all enzymes e) All relevant cofactors/co-substrates discussed in class, clearly showing, where ATP is used and produced f) Double or single arrows representing reversible or irreversible reactions, respectively g) All "high-energy" intermediates clearly labeled with an asterisk (*) h) Labels for cellular locations of…arrow_forwardBiosynthesis of fatty acid 20:D6 from acetyl-CoA occurs in the __________ of mammalian cells. Cytosol Endoplasmic reticulum Both A and B Neither A nor B Assuming all three carbon atoms of glycerol are labeled as C14 radioisotopes and the radioisotope-labeled glycerol undergoes metabolism in animals. All of the following molecules in the animal maycontain C14 radioisotopes EXCEPT: Pyruvate Acetyl-CoA Glutamine Fatty acids Oxaloacetate All of the above molecules may contain C14 radioisotopearrow_forward
- BiochemistryBiochemistryISBN:9781305577206Author:Reginald H. Garrett, Charles M. GrishamPublisher:Cengage Learning