线粒体脂肪酸β-氧化
中文名称
通路描述
β-氧化一旦脂肪酸被肉碱酰转移酶导入线粒体基质中就开始。脂肪酸代谢的β-氧化螺旋涉及从脂肪酸酰链上重复移除两个碳单元。该过程共有四个步骤：氧化、水合、第二次氧化和最后硫解。最后一个步骤释放两个碳的乙酰-CoA和一个处于激活状态的酰-CoA，后者将再次沿着螺旋向下转动。每个β-氧化螺旋的完整转动产生一个NADH、一个FADH2和一个乙酰-CoA。乙酰-CoA的进一步氧化通过三羧酸循环产生额外的FADH2和NADH。所有还原的辅因子都由线粒体电子传递链形成ATP。脂肪酸分子的完全氧化产生大量ATP分子。此处以棕榈酸为模型，产生129个ATP。饱和脂肪酸和不饱和脂肪酸的β-氧化途径不同。饱和脂肪酸的β-氧化需要四个不同的酶促步骤。β-氧化产生和消耗具有反式构型的中间体；具有顺式构型键的不饱和脂肪酸需要三个酶促步骤来为β-氧化途径做准备。
英文描述
Mitochondrial Fatty Acid Beta-Oxidation Beta-oxidation begins once fatty acids have been imported into the mitochondrial matrix by carnitine acyltransferases. The beta-oxidation spiral of fatty acids metabolism involves the repetitive removal of two carbon units from the fatty acyl chain. There are four steps to this process: oxidation, hydration, a second oxidation, and finally thiolysis. The last step releases the two-carbon acetyl-CoA and a ready primed acyl-CoA that takes another turn down the spiral. In total each turn of the beta-oxidation spiral produces one NADH, one FADH2, and one acetyl-CoA.Further oxidation of acetyl-CoA via the tricarboxylic acid cycle generates additional FADH2 and NADH. All reduced cofactors are used by the mitochondrial electron transport chain to form ATP. The complete oxidation of a fatty acid molecule produces numerous ATP molecules. Palmitate, used as the model here, produces 129 ATPs.Beta-oxidation pathways differ for saturated and unsaturated fatty acids. The beta-oxidation of saturated fatty acids requires four different enzymatic steps. Beta-oxidation produces and consumes intermediates with a trans configuration; unsaturated fatty acids that have bonds in the cis configuration require three separate enzymatic steps to prepare these molecules for the beta-oxidation pathway.
所含基因
21 个基因