Assays of pyruvate dehydrogenase complex and pyruvate carboxylase activity.
Pyruvate dehydrogenase complex (PDC) and pyruvate carboxylase (PC) are mitochondrial enzymes that provide the initial steps of the two main alternatives for pyruvate metabolism: oxidative decarboxylation vs. anaplerotic carboxylation, gluconeogenesis, and glycerogenesis. Assays of the enzymatic activity of these two enzymes in cells and tissues are described in this chapter, based on evolution or fixation of (14)CO(2). These assays are both suitable for use in crude homogenates of cultured skin fibroblasts, lymphocytes, and frozen muscle (PDC) or liver (PC). Activities of these two enzymes are related to spectrophotometric assays of two other mitochondrial enzymes, dihydrolipoamide dehydrogenase (E3) and citrate synthase (CS), providing initial indices of sample integrity and mitochondrial content. These parameters have proven useful for initial detection of inherited human disorders due to deficiencies of these enzymes, and in combination with available genetic analyses can lead to confirmation of specific diagnoses.
Center for Inherited Disorders of Energy Metabolism, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, OH, USA. douglas.kerr@case.edu
Douglas
D
Kerr
George
G
Grahame
Ghunwa
G
Nakouzi
D000328:Adult; D000818:Animals; D002675:Child, Preschool; D002950:Citrate (si)-Synthase / Q000378:metabolism; D008058:Dihydrolipoamide Dehydrogenase / Q000378:metabolism; D057075:Enzyme Assays / Q000379:methods*; D006801:Humans; D007223:Infant; D011766:Pyruvate Carboxylase / Q000378:metabolism*; D011768:Pyruvate Dehydrogenase Complex / Q000378:metabolism*
D011768:Pyruvate Dehydrogenase Complex; D008058:Dihydrolipoamide Dehydrogenase; D002950:Citrate (si)-Synthase; D011766:Pyruvate Carboxylase