tailieunhanh - Biochemistry, 4th Edition P114

Biochemistry, 4th Edition P114. Continuing Garrett and Grisham's innovative conceptual and organizing framework, "Essential Questions," BIOCHEMISTRY guides students through course concepts in a way that reveals the beauty and usefulness of biochemistry in the everyday world. Streamlined for increased clarity and readability, this edition also includes new photos and illustrations that show the subject matter consistently throughout the text. New end-of-chapter problems, MCAT practice questions, and the unparalleled text/media integration with the power of CengageNOW round out this exceptional package, giving you the tools you need to both master course concepts and develop critical problem-solving skills you can draw upon. | Abbreviated Answers to Problems A-33 16. See the following mechanisms. a-Methyleneglutarate mutase H H _ I _ I -OOC C CH2 -OOC c ch2 OI C COO - C COO II ch2 B12 ch2 H . . I OOC C CH2 c coO A II H CH2 B12 H . . I OOC C CH C COO- II CH2 Diol dehydrase HH I I H3C CH C OH - H3C CH C OH OH H OH H H3C CH2 C 2 h2o Glycerol dehydrase H I CH2 CH C H I I I V OH OH OH B12 H I CH2 CH C- I I I OH OH OH CH2 CH C-Ch ------ CH2 CH2 CZ 1 V I 2 2 OH O H OH O B12 h B H2O Ethanolamine ammonia-lyase H I H I CH2 C H ----- CH2 C- I I V nh3 oh nh3 oh B12 H I O b h C -c-0 nh3 b h I CH3 C 3 B H NH4 A-34 Abbreviated Answers to Problems 17. V h2c c ch gh2 c coo I nh3 Hypoglycin A CoASH v o O H3C. II .CH2 II C CH CH C SCoA II H2C H2C C CH CH2 C SCoA 2 Reactive intermediate 18. This exercise is left to the student and should be based on the reference provided in the problem. 19. It may be presumed that the oxidation of the acyl chain is accomplished via a two-electron transfer whereas the steps involved in reoxidation of FADH2 by ETF are one-electron transfers. FAD FADH2 can participate both in one-electron and two-electron transfers whereas NAD NADH can participate only in two-electron transfers. 20. The sequence of reactions involving creation of a double bond then hydration across it followed by oxidation is what happens to succinate in the TCA cycle. This same sequence of reactions is also employed in fatty acid synthesis and in both the catabolism and anabolism of amino acids. Clearly this sequence of three reactions must represent an optimal mechanistic strategy for the chemistry achieved. Chapter 24 1. The equations needed for this problem are found on page 730. See The Student Solutions Manual Study Guide and Problems Book for details. 2. Carbons C-1 and C-6 of glucose become the methyl carbons of acetyl-CoA that is the substrate for fatty acid synthesis. Carbons C-2 and C-5 of glucose become the carboxyl carbon of acetyl-CoA for fatty acid synthesis. Only citrate that is immediately .