5. In the subsequent stages of glycolysis (see figure below): (1) cleavage of FBP to dihydroxyacetone (DHP) and glyceraldehyde 3-phosphate (G3P) according to FBP → DHP + G3P is catalyzed by aldolase with K₁= 10+ and (2) the DHP and G3P can interconvert (DHP → G3P), a process catalyzed by triose phosphate isomerase with K₂ = 0.040. If a 1.75 mM solution of FBP is treated with both of these enzymes (enabling both of these reactions) at pH 7 and 37°C, find the resulting equilibrium concentration of each species.

In the glycolytic pathway, a six-carbon sugar (fructose 1,6-bisphosphate) is cleaved to form two three-carbon sugars, which undergo further metabolism . In this pathway, an isomerization of glucose 6-phosphate tofructose 6-phosphate (shown below) occurs two steps before the cleavage reaction (the intervening step is phosphorylation of fructose 6-phosphate to fructose 1,6-bisphosphate ). What does the isomerization step accomplish from a chemical perspective? (Hint: Consider what might happen if the C—C bond cleavage were to proceed without the preceding isomerization.)

4. The AGo for the aldolase reaction is 22.8 kJ/mol. When the reaction is run in a hepatocyte cell at 37°C, the concentrations of the intermediates are: fructose 1,6-bisphosphate =1.41 x 103 M, glyceraldehyde 3-phosphate 2.95 x 10-6 M, and dihydroxyacetone phosphate = 1.62 x 10-5 M. Calculate the free energy change for this reaction Is this reaction thermodynamically favorable

Step 7 of the citric acid cycle is shown. Which statement best describes what occurs in this step? CO₂ 1 CH || CH + H₂O CO₂ fumarate CO₂™ fumarase HO C-H CH₂ CO₂ malate A) Fumarate undergoes hydrogenation with hydrogens and electrons provided by the enzyme fumarase. B) Fumarate undergoes hydration with the aid of the enzyme fumarase. C) Fumarate undergoes hydrolysis with the aid of the enzyme fumarase. D) Fumarate undergoes reduction with the aid of the cofactor fumarase.

The enzyme that catalyzes reaction below can be classified as: NAD* NADH + H* Но- H-Ć- Н—с—н H- malate dehydrogenase Oxaloacetate Malate

Identify the most likely additional substrates, products, and coenzymes for each reaction in the following imaginary pathway.

Gluconeogenesis in humans involves many of the enzymes of glycolysis working in a reverse direction, but utilizes four unique enzymes. (a) Draw these four reactions at pH 7, indicating the reactants and products, and the full name of the enzyme. You are required to draw the structures of the products and reactants for the first two reactions in gluconeogenesis and their full names but only provide the full names on the remaining two reactions. You do not have to draw the structures of any cofactors just use their abbreviations.

Anaerobic glycolysis (i.e., lactic acid fermentation) produces pyruvate that is then converted to lactate through the activity of lactate dehydrogenase. The conversion of pyruvate to lactate would seem to be an unnecessary step, since this process does not result in any further release of energy. Explain the necessity for the production of lactate as the endpoint for anaerobic glycolysis.

In the citric acid cycle, a - ketoglutarate dehydrogenase catalyzes the reaction from a - ketoglutarate to Succinyl CoA. Given this reaction, calculate for the enthalpy of formation of the product using (a) Hess's Law, (b) standard enthalpies of formation and (c) mean bond enthalpies. Show your complete solution. COA-S OOC CH2 CH2 + NAD++ COA + CO2 + NADH CH2 a-ketoglutarate CH2 dehydrogenase COO a-ketoglutarate COO Succinyl CoA

The hydrolysis of pyrophosphate to orthophosphate drives biosynthetic reactions such as DNA synthesis. In Escherichia coli, a pyrophosphatase catalyzes this hydrolytic reaction. The pyrophosphatase has a mass of 120 kDa and consists of six identical subunits. A unit of activity for this enzyme, U, is the amount of enzyme that hydrolyzes 10 umol of pyrophosphate in 15 minutes. The purified enzyme has a Vnax of 2800 U per milligram of enzyme. When (S] >> KM, how many micromoles of substrate can 1 mg of enzyme hydrolyze per second? Vnax = umol -s. mg- If cach enzyme subunit has one active site, how many micromoles of active sites, or (E]r, are there in 1 mg of enzyme? (Er = umol - mg-