Biochemical and molecular investigations in respiratory chain deficiencies

This paper describes our present strategy for the investigation of respiratory chain disorders in humans. Because very few of the underlying mutations causing ~tochond~al disorders in humans are currently known, biochemical studies constitute a major tool in screening pro-cedures for respiratory chain deficiencies. All biochemical and molecular methods described are scaled-down methods, allowing investigation in both adults and young children. Polaro-graphic studies and/or spectrophotometric studies on whole cells (circulating lymphocytes), isolated mitochondria {skeletal muscle) and tissue homogenates are presented. Advantages and l~itations of each approach, as well as useful parameters for the chara~ter~tion of de-fects and comparison between various tissues are discussed. Keywar & Human mitochondria; Respiratory chain defects; Mitochondria isolation; Cell res-piration; Polarography; Spectrophotometr