Iodoacetic acid glycolysis

How might iodoacetic acid affect the glyceraldehyde-3-phosphate dehydrogenase reaction in glycolysis Justify your answer. 

Identification of the energy source for muscle contraction and determination of the order in which the phosphate esters were metabolized was helped by the use of inhibitors. These inhibitors blocked different stages in glycolysis and caused preceding substrates to accumulate in quantities which could greatly exceed those normally present. The compounds were then isolated, identified, and used as specific substrates to identify the enzymes involved in their metabolism. Iodoacetic acid (IAc) was one of the most important inhibitors used to analyze glycolysis. 

In 1930 Lundsgaard discovered that glycolysis is totally arrested by iodoacetic acid (lAA) and yet he found the alactacid muscles able to perform a considerable amount of work before they became exhausted in a state of rigor which also was alactacid. The 30-year-young physiologist published within 1 year a series of most creative articles. 

The conversion, by bacterial extracts, of D-oZtro-heptulose 1,7-diphosphate to shikimate, essentially without side reactions, greatly facilitated subsequent study of the intermediate steps in the synthesis. It was shown that the addition of iodoacetate or fluoride completely blocks this conversion. In the presence of iodoacetate, synthesis is restored by the addition of either D-glyceronic acid 3-phosphate or enolpyruvate phosphate. In the presence of fluoride, only enolpyruvate phosphate is able to restore shikimate synthesis. Neither D-fructose 1,6-diphosphate nor pyruvate reverses these inhibitions. These results suggested that the reactions of glycolysis, from triose phosphate to enolpyruvate phosphate (see Fig. 2), are involved in the conversion of D-oZfro-heptulose diphosphate to shikimate. The effect... 

It was found by the use of inhibitors that the circumstance noce.s.sary for nactivation of pantothenate was not only that glucose should be present, but that it should be broken down by the streptococci. The organisms produced from glucose, with or without pantothenate, about 1.9 moles of lactic acid per mole of glucose. Such glycolysis, and pantothenate breakdown, proceeded aerobically or anaerobically, but, when it was inhibited by iodoacetate, benzene, malonate, or propamidine, the reaction with pantothenate was also inhibited. The streptococcal extracts in which pantothenate was stable were also incapable of glycolysis. 

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