Myogenic Disease and Metabolic Acidosis: Consider Multiple Acyl-Coenzyme A Dehydrogenase Deficiency

Figure 4

Simplified illustration of the mitochondrial respiratory chain. The respiratory chain is an electron transport chain that oxidizes reduced coenzymes (such as NADH) resulting from the degradation of organic compounds. It is composed of four protein complexes (I–IV) located in the inner mitochondrial membrane. The complexes are associated with two cofactors, coenzyme Q10 (Q) and cytochrome (C). This oxidation provides the energy required for proton transfer from the matrix to the mitochondrial intermembrane space. The resulting electrochemical gradient provides the energy needed for ATP synthase to phosphorylate ADP to ATP. The enzymes’ electron transfer flavoprotein (ETF) and ETF dehydrogenase (ETFDH) catalyze the transfer of electrons produced by fatty acid oxidation from acyl-coenzyme A dehydrogenase to coenzyme Q10, using flavin adenine dinucleotide (FAD) as a cofactor.