Complex II Is Complex Too

Abstract

In aerobic eukaryotic cells, the respiratory chain of enzymes in the inner mitochondrial membrane transfers electrons from NADH and succinate to molecular oxygen, in the process producing the energy-rich molecule ATP. Hederstedt explains in his Perspective that the crystal structure of bacterial SQR (equivalent to mitochondrial complex II) reveals how the arrangement of redox centers in this enzyme enables electrons to be transferred to ubiquinone while minimizing production of reactive oxygen species that could damage tissues (Yankovskayaet al.).