BIO 361 Lecture 25: LECTURE 25B BIOCHEM
10 Jul 2016
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Document Summary
The first enzyme involved in the krebs cycle is associated with uncompetitive inhibition. The order of substrate binding is therefore obligate. The order of binding for citrate synthase is oxaloacetate first. There is an open structure to the enzyme until it binds the oxaloacetate to undergo a conformational change. This new enzyme with an oxaloacetate can now bind for acetyl-coa. There is no binding site for acetyl-coa in the free enzyme. The synthesis of citrate is the product of oxaloacetate and acetyl-coa binding. The product of the next enzyme in the krebs cycle is isocitrate which is not symmetrical. The problem for the enzyme imposed on the asymmetrical substrate isocitrate is moving the hydroxyl from the 2- to the 1-position, which is not a very energetically demanding reaction. What actually is a challenge, is to make a stereospecific product of isocitrate. The trick for doing that has been around and is called an augsten (?)
