Energy release from fat

This chapter shows the way that energy is released from fat involving the oxidation of fatty acids released from triacylglycerols. These are first converted into fatty acyl-Coenzyme As (CoAs). Then the acyl groups are transported into the mitochondria. The chapter emphasizes that fatty acyl-CoA cannot enter the mitochondrion, but an enzyme of the outer membrane transfers it to carnitine and a transport system transfers the acylcarnitine into the matrix where another enzyme transfers the acyl group back to CoA. In the matrix, the fatty acyl-CoA is converted into acetyl-CoA by a process called β-oxidation in which carbon atoms are released two at a time in the form of acetyl-CoA. The chapter describes the fatty acid chain of acyl-CoAs, which is dehydrogenated by a series of enzymes that produce β-ketoacyl-CoAs. Acetyl units are split off by the enzyme ketoacyl-CoA thiolase, which attaches each to CoASH and releases acetyl-CoA.