MECHANISM FIGURE 14-7 The glyceraldehyde 3-phosphate dehydrogenase reaction. After ©formation of the enzyme-substrate complex, ©a covalent thiohemiacetal linkage forms between the substrate and the —SH group of a Cys residue—facilitated by acid-base catalysis with a neighboring base catalyst, probably a His residue. ©This enzyme-substrate intermediate is oxidized by NAD+ bound to the active site, forming a covalent acyl-enzyme intermediate, a thioester. ©The newly formed NADH leaves the active site and is replaced by another NAD+ molecule. The bond between the acyl group and the thiol group of the enzyme has a very high standard free energy of hydrolysis. ©This bond undergoes phosphorolysis (attack by P|), releasing the acyl phosphate product, 1,3-bisphosphoglycerate. Formation of this product conserves much of the free energy liberated during oxidation of the aldehyde group of glyceraldehyde 3-phosphate.

7 Phosphoryl Transfer from 1,3-Bisphosphoglycerate to ADP

The enzyme phosphoglycerate kinase transfers the high-energy phosphoryl group from the carboxyl group of 1,3-bisphosphoglycerate to ADP, forming ATP and 3-phosphoglycerate:


Diabetes 2

Diabetes 2

Diabetes is a disease that affects the way your body uses food. Normally, your body converts sugars, starches and other foods into a form of sugar called glucose. Your body uses glucose for fuel. The cells receive the glucose through the bloodstream. They then use insulin a hormone made by the pancreas to absorb the glucose, convert it into energy, and either use it or store it for later use. Learn more...

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