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Biochemistry, 4th Edition P76

Biochemistry, 4th Edition P76. 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. | 23.4 How Are Unsaturated Fatty Acids Oxidized 713 H COO- I HO C H NADP NADPH I O __ ch2 I _ C. OX O- Malate Oxaloacetate enzyme-bound CO2 COO- O C H Ch3 Pyruvate CENGAGENOW Go to CengageNOW and click CengageInteractive to interact with a mechanism for the methylmalonyl mutase reaction. FIGURE 23.20 The malic enzyme reaction proceeds by oxidation of malate to oxaloacetate followed by decarboxylation to yield pyruvate. 23.4 How Are Unsaturated Fatty Acids Oxidized An Isomerase and a Reductase Facilitate the -Oxidation of Unsaturated Fatty Acids Unsaturated fatty acids are also catabolized by ß-oxidation but two additional mitochondrial enzymes an isomerase and a novel reductase are required to handle the cis double bonds of naturally occurring fatty acids. As an example consider A DEEPER LOOK Can Natural Antioxidants in Certain Foods Improve Fat Metabolism Numerous beneficial effects have been attributed in recent years to the polyphenolic compounds in foods such as chocolate red wine and black or green tea. Principal among these compounds are the catechins a class of antioxidants that have demonstrated protective effects against certain cancers obesity and heart disease as well as other beneficial health effects. Is it possible to demonstrate specific effects of catechins on cellular metabolism Takatoshi Murase and his colleagues have shown that green tea extract consisting almost entirely of six catechins shown in the figure added to the diets of rats increased muscle glycogen content decreased muscle fatty acid synthesis and increased fatty acid oxidation by rat skeletal muscle by 36 . In these same rats exercise endurance capacity for swimming and running increased significantly suggesting that fatty acids can be an effective source of energy in exercising muscle. Measurements of the catechin content of a range of teas wines and other beverages indicate that the broadest range and the highest levels of these compounds are found in tea but that red wine has