Coupling ATP hydrolysis to glucose phosphorylation makes thermodynamic sense, but consider how the coupling mighttake place.Given that coupling requires a common intermediate, one conceivable mechanism is to use ATP hydrolysis to raise theintracellular concentration of P,. The increase in P, concentration would drive the unfavorable phosphorylation of glucose by P.Is increasing the P concentration a reasonable way to couple ATP hydrolysis and glucose phosphorylation?No. The phosphate salts of divalent cations would be present in excess and precipitate out.Yes. The extra ATP hydrolysis would provide enough free energy to drive the phosphorylation reaction.Yes. Increasing the concentration of P, would decrease K'e and shift equilibrium to the right.No. The extra P, would give a negative AG, but would give a positive AG.In hepatocytes, the enzyme glucokinase catalyzes the ATP-coupled phosphorylation of glucose. Glucokinase binds both ATPand glucose, forming a glucose-ATP-enzyme complex. The enzyme then transfers the phosphoryl group directly from ATPto glucose.In hepatocytes, the enzyme glucokinase catalyzes the ATP-coupled phosphorylation of glucose. Glucokinase binds both ATPand glucose, forming a glucose-ATP-enzyme complex. The enzyme then transfers the phosphoryl group directly from ATPto glucose.Select the advantages of phosphoryl group transfer compared to hydrolysis and subsequent phosphorylation?O Reaction intermediates do not need to be present in excess.Glucokinase increases the transition state energy, favoring glucose phosphorylation.O ATP hydrolysis is thermodynamically unfavorable compared to group transfer.The process takes advantage of the high phosphoryl group transfer potential of ATP.

ATP+ HOH -------> ADP+ Pi ∆G = -7 kcal/mol Glucose + Pi –------> glucose 6 phosphate + ADP…

Answered: intracellular concentration of P. The…

Biochemistry

6th Edition

ISBN:9781305577206

Author:Reginald H. Garrett, Charles M. Grisham

Publisher:Reginald H. Garrett, Charles M. Grisham

Chapter23: Fatty Acid Catabolism

Section: Chapter Questions

Problem 21P: Using the ActiveModel for enoyl-CoA dehydratase, give an example of a case in which conserved...

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Figure 27.3 illustrates the response of R (ATP-regenerating) and U (ATP-utilizing) enzymes to energy charge. a. Would hexokinase be an R enzyme or a U enzyme? Would glutamine: PRPP amidotransferase, the second enzyme in purine biosynthesis, be an R enzyme or a U enzyme? b. If energy charge = 0.5: Is the activity of hexokinase high or low? Is ribose-5-P pyrophosphokinase activity high or low? c. If energy charge = 0.95: Is the activity of hexokinase high or low? Is ribose-5-P pyrophosphokinase activity high or low?
Distinguishing 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.
The Reactions and Meehanisms of the Leloir Pathway Write the reactions that permit galactose to be utilized in glycolysis. Write a suitable mechanism, tor one of these reactions.
Both prokaryotic and eukaryotic organisms carry out some form of glycolysis. How does ha fact support or not support the assertion that glycolysis is one of the oldest metabolic pathways?
Examine the ActiveModel for alcohol dehydrogenase and describe the structure and function of the catalytic zinc center.
Based on your knowledge of the structure of NAD+ and an assumption that coenzyme dissociation is the rate limiting step of the alcohol dehydrogenase mechanism, hypothesize why a N249W mutation at the coenzyme binding site would increase the rate of catalysis.
Based on your residing of this chapter, what would you expect to be the most immediate effect oil glycolysis, if the steady-state concentration of gJucose-6-P were 8.3 mM instead of 0.083 mM?
The Catabolism of Uric Acid Write a balanced equation for the oxidation of uric acid to glyoxylic acid, CO2, and NH3, showing each step in the process and naming all of the enzymes involved.
The Energetic Cost of Nitrogen Excretion via the Urea Cycle How many ATP equivalents are consumed in the production of 1 equivalent of urea by the urea cycle?
The Relative Efficiency of ATP Synthesis in Noncyclic versus Cyclic Photophosphorylation If noncyclic photosynthetic electron transport leads to the translocation of 7 H+/2e- and cyclic photosynthetic electron transport leads to the translocation of 2 H+/e-, what is the relative photosynthetic efficiency of ATP synthesis (expressed as the number of photons absorbed per ATP synthesized) for noncyclic versus cyclic photophosphorylation? (Assume that the CF1CF0-ATP synthase yields 3 ATP/14 H+.)
Using the ActiveModel for aldose reductase, describe the structure of the TIM barrel motif and the structure and location of the active site.
Comparing Glycolysis Entry Points for Sucrose Sucrose can enter glycolysis by either of two routes: Sucrose phosphorylase: Sucrose + Pi fructose + glucose-1-phosphate Invertase: Sucrose + H20 fructose + glucose Would either of these reactions offer Jin advantage over the other In the preparation of hexoses fur entry into glycolysis?

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