2. The discovery that glyceraldehyde-3-phosphate dehydrogenase is irreversibly i

Question

2. The discovery that glyceraldehyde-3-phosphate dehydrogenase is irreversibly inhibited by iodoacetate was important in the history of research on glycolysis. Explain the effect of this inhibitor in skeletal muscle on a) The overall flux through glycolysis; b) The relative concentrations of intermediates of the glycolytic pathway; c) The net production/utilization of ATP by glycolysis and the pathway efficiency; d) The synthesis of triacylglycerol; e) If iodoacetate was able to inhibit lactate dehydrogenase instead of glyceraldehyde- 3-phosphate dehydrogenase, would the muscle be able to generate ATP by glycolysis at a high enough rate for strenuous physical activity? Explain

Explanation / Answer

a.

process of glycolysis pyruvate is produced which undergo Kreb cycle and produce NADH2.

glycolysis is inhibited then the production of NADH2 is also reduced.

the occurrence of NAD is high.

So the flux is reduced.

b. in the glycolysis glucose is converted into Fructose 6 phosphate and Fructose 6 phosphate is converted into Fructose 1 6 bisphosphate. These F 16 BP undergo breakdown and form glyceraldehyde 3 phosphate. This glyceraldehyde 3 phosphate is reduced by the enzyme glyceraldehyde 3 phosphate dehydrogenase. when this enzyme is not active then the high amount of glyceraldehyde 3 phosphate and dihydroxyacetone phosphate is occured.

Due to the high concentration of these components amount of fructose 1 6 bisphosphate is also enhanced. these all it helps concentration reduces or inhibites the conversion of glucose into glucose 6 phosphate.

NAd is available in high concentration because no conversion of this into reduced form because of blocked pathway.

c. when glyceraldehyde 3 phosphate enzyme does not works then the process cannot continue for the formation of pyruvate. when pyruvate is not formed then citric acid cycle is not appeared. the concentration of ATP is reduced in the cell and the concentration of ADP and NAD + is high in cell. The pathway will blocked in the upper steps of glycolysis. when the amount of glucose is highly reduced then no conversion of glucose into glucose 6 phosphate.

not a single ATP production because of the inhibitor who inhibited the glyceraldehyde 3 phosphate dehydrogenase enzyme.

Henece no production of ATP.

but utilisation of ATP occurred in the conversion of glucose to glucose 6 phosphate. and the conversion of fructose 6 phosphate to Fructose 1 6 bisphosphate.

So 2 molecules of ATP is required in the 2 phosphorylation steps.

d. the triacylglycerol is glyceraldehyde 3 phosphate. this is produced by the breakdown of fructose 1 6 bisphosphate.

Fructose 1 6 bisphosphate undergo breakdown and produce glyceraldehyde 3 phosphate and dihydroxyacetone phosphate molecules.

the next enzyme for the conversion of glycerol 3 phosphate dehydrogenase is unavailable due to inhibition then the high concentration of these triacylglycerols occurred.

e. yes lactate dehydrogenase do the dehydrogenation of lactate.

lactate dehydrogenase is an enzyme which forms lactate from pyruvate.

During high muscular activity oxygen is not available and Piruvatis not able to run club cycle because of the unavailability of NAD. this all happens due to less availability of oxygen.

During high muscular activities the supply of oxygen to muscle cells is not proper.

So the pyruvate is convertedpyruvate is converted into elected by theelected by the enzyme lactate dehydrogenase.

when lactate dehydrogenase is nhibited then lactate is not prproduced then the hhigh amount of pyruvate is accumulated iin cell. In other side it is not conveted into acetyl co. EA because no availability of NAD.

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