title: Obesity affects mitochondrial citrate synthase in human omental adipose tissue.
abstract: The activities of some key enzymes in mitochondria from 135 human omental adipose tissue samples of obese and nonobese patients were analyzed for potential association with the patients' state of obesity. The activities of respiratory complexes I and II as well as citrate synthase in isolated mitochondria were measured using spectrophotometric enzyme assays. ATP generation of mitochondria was determined with a bioluminescence assay. Protein levels of citrate synthase were quantified by western blot. The rates of ATP generation and the enzymatic activities of complexes I and II did not display associations with age, gender, obesity, or diabetes. By contrast, the enzymatic activities of citrate synthase and its protein levels were significantly reduced in obesity as compared to controls. In diabetic patients, protein levels but not enzymatic activities of citrate synthase were elevated. Thus, this investigation based on enzymatic assay and determination of protein levels revealed that the development of obesity is associated with a significant impact on citrate synthase in mitochondria of human omental adipose tissue. The state of obesity appears to affect mitochondrial function in human omental adipose tissue by limiting this key enzyme of the tricarboxylic acid cycle rather than by limiting the activities of respiratory chain enzymes.
authors.affiliation: Laboratory of Endocrinology, Department of Biomedicine, University Hospital and University Children's Hospital, Hebelstraße 20, 4031 Basel, Switzerland.
authors.forename: Martine
authors.initials: M
authors.lastname: Christe
authors.affiliation: Laboratory of Endocrinology, Department of Biomedicine, University Hospital and University Children's Hospital, Hebelstraße 20, 4031 Basel, Switzerland ; Laboratory of Clinical Pharmacology and Toxicology, Department of Biomedicine, University Hospital Basel, Hebelstraße 20, 4031 Basel, Switzerland.
authors.forename: Estelle
authors.initials: E
authors.lastname: Hirzel
authors.affiliation: Surgical Department, St. Claraspital, Kleinriehenstraße 30, 4058 Basel, Switzerland.
authors.forename: Andrea
authors.initials: A
authors.lastname: Lindinger
authors.affiliation: Surgical Department, St. Claraspital, Kleinriehenstraße 30, 4058 Basel, Switzerland.
authors.forename: Beatrice
authors.initials: B
authors.lastname: Kern
authors.affiliation: Surgical Department, St. Claraspital, Kleinriehenstraße 30, 4058 Basel, Switzerland.
authors.forename: Markus
authors.initials: M
authors.lastname: von Flüe
authors.affiliation: Surgical Department, St. Claraspital, Kleinriehenstraße 30, 4058 Basel, Switzerland.
authors.forename: Ralph
authors.initials: R
authors.lastname: Peterli
authors.affiliation: Interdisciplinary Center of Nutritional and Metabolic Diseases, St. Claraspital, Kleinriehenstraße 30, 4058 Basel, Switzerland.
authors.forename: Thomas
authors.initials: T
authors.lastname: Peters
authors.affiliation: Laboratory of Endocrinology, Department of Biomedicine, University Hospital and University Children's Hospital, Hebelstraße 20, 4031 Basel, Switzerland ; Collegium Helveticum, ETH Zentrum, 8092 Zurich, Switzerland.
authors.forename: Alex N
authors.initials: AN
authors.lastname: Eberle
authors.affiliation: Laboratory of Endocrinology, Department of Biomedicine, University Hospital and University Children's Hospital, Hebelstraße 20, 4031 Basel, Switzerland ; Laboratory of Clinical Pharmacology and Toxicology, Department of Biomedicine, University Hospital Basel, Hebelstraße 20, 4031 Basel, Switzerland.
authors.forename: Peter W
authors.initials: PW
authors.lastname: Lindinger