Tribute to Bernhard Kadenbach – Cytochrome c oxidase: from subunits to regulatory functions

Bernhard Kadenbach was a German biochemist whose research advanced our understanding of mitochondrial cytochrome c oxidase (Complex IV, CIV) and its regulation. In the 1980s, he discovered that mammalian CIV consists of 13 tightly bound subunits, a finding later confirmed through structural analysis. Besides the structural studies of CIV, his research focused on the role of tissue-specific isoforms of CIV subunits, its allosteric regulation by the ATP/ADP ratio, and phosphorylation mechanisms, proposing a “second mechanism of respiratory control” that modulates energy transformation and minimizes reactive oxygen species (ROS). Kadenbach’s insights into CIV regulation, tissue-specific isoforms, and metabolic control remain influential for ongoing mitochondrial research and potential therapeutic applications.