Four key enzymes in the citric acid cycle 1 pyruvate

This preview shows page 2 - 4 out of 4 pages.

Four Key Enzymes in the Citric Acid Cycle 1. Pyruvate Dehydrogenase Complex (PDH) " step O". Oxidative decarboxylation produces CO 2 and NADH. The acetyl-CoA product is a ("high-energy") thioester. The structure of the "complex" is complex (Fig. 16.5). The four separate reactions are complex (Fig. 16.4). Note the "swinging arm" of reactions 2-4. Regulation a. ATP and NADH are inhibitors. b. Phosphorylation of PDH inhibits the reaction. c. Ca 2+ activates the dephosphorylation. 2. Citrate Synthase: step 1. Irreversible condensation reaction. Allosteric inhibitors: ATP and NADH. Recall that citrate (in the cytosol) is an inhibitor of PFK in glycolysis. 3. Isocitrate Dehydrogenase: step 3. Oxidative decarboxylation produces CO 2 and NADH. The α -ketoglutarate product is a 5-carbon dicarboxylic acid. Regulation Allosteric inhibitors: ATP and NADH. Allosteric activators: ADP and NAD + . 4. α -Ketoglutarate Dehydrogenase Complex: step 4. Oxidative decarboxylation produces CO 2 and NADH. The succinyl-CoA product is a thioester. The complex is similar to the PDH complex.
Image of page 2

Subscribe to view the full document.

3 The remaining reactions in the cycle (steps 5-8) serve to regenerate oxaloacetate for step 1.
Image of page 3
Image of page 4
You've reached the end of this preview.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern