TABLE 142 FreeEnergy Changes of Glycolytic Reactions in Eryt

TABLE 14-2 Free-Energy Changes of Glycolytic Reactions in Erythrocytes AG AWmo) Glycolytic reaction step AG\" (kl/mo) O Glucose ATP gucose 6-phosphate ADP 16.7 2 Glucose 6phosphate urn fructose 6phosphate 0 to 25 1.7 Fructose 6phosphate ATP fructose 1.6bisphosphate ADP 3 14.2 (4 Fructose 1,6- hydroyacetone phosphate glyceraldehyde 3-phosphate 238 0 to -6 S Dihydroxyacetone phosphate oyceraldehyde 3phosphate 0 to 4 (6 Glyceraldehyde 3phosphate +P+ NAD 1.3bisphosphog yoerate H 2 to 2 (7) 13 Bisphosphogycerate ADP 3phosphogycerate ATP 18.8 0 to 2 O 3Phosphoglycerate 2-phosphoglycerate 0 to 0.8 2 -Phosphoglycerate urm phosphoenolpyruvate H70 75 0 to 33 10 Phosphoenolpymuvate ADP pyruvate ATP 31.4 -167 1. Examine the data above and succinctly answer the following questions a. What do reactions 1, 3. and 10 have in common? b. What is the significance of this commonality on the overall biochemical pathway these reactions are involved in? c. If the concentrations of glucose and ATP in reaction 1 were both 1uM, what must the minimal concentrations of glucose 6-phosphate and ADP be to drive the reaction in the reverse direction at 250 Celsius?

Solution

a. in step 1 glucose is phosphorylated by ATP to form glucose-6-phosphate, so it is a phosphoryl transfer type reaction.

in step 3 phosphorylation of Frutose-6-Phosphate occur, it also by ATP.

In step 10 the enzyme pyruvate kinase catalyses the transfer of a phosphoryl group from PEP to ADP.

STEPS 1,3,10 ALL ARE IRREVERSIBLE.

b.in metabolic pathways irreversible reactions are the control sites. Hexokinase, PHOSPHOFRUCTOKINASE, Pyruvate Kinase are have regulatory and catalytic role.

.C. we have to calculate the GIBBS FREE ENERGY, if it have a positive value the reaction will be reversible. assume the unknown conc as x.