BIO 361 Study Guide - Midterm Guide: Aconitase, 2-Phosphoglyceric Acid, Hydrophobe
20 Sep 2016
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Glycolysis: the 1st reaction is an irreversible phosphorylation of glucose at the 6th carbon using hexokinase that consumes atp to make glucose-6-phosphate (g6p) Glucose binding causes a large conformational shift that excludes water and brings 6"- Atp would rather be hydrolyzed by water but hydrophobicity and proximity prevents this. The 2nd reaction is a reversible rearrangement of g6p (isomerization reaction) using phosphoglucose isomerase (pgi) to fructose-6-phosphate (f6p) This is possible through independent modulation of 6-phosphates. Isomerization because reactants and products are hemiacetals and hemiketals respectively. A cis-enediolate intermediate is made and involves the movement of a carbonyl double bond from the 1- to the 2-position. Subsequent ring closure through intramolecular attack results in f6p. The 3rd reaction is an irreversible phosphorylation of f6p at the 1st carbon using phosphofructokinase (pfk) that consumes atp to make fructose-1,6-biphosphate (fbp) Fbp can still be hydrolyzed to f6p but only using a different enzyme.
