title: Enzyme kinetics for systems biology when, why and how.
abstract: In vitro enzymatic assays of cell-free extracts offer an opportunity to assess in vivo enzyme concentrations. If performed under conditions that resemble the conditions in vivo, they may also reveal some of the capacities and properties of the same enzymes in vivo; we shall call this the ex vivo approach. The kinetic characterization of purified enzymes has yet a different utility for systems biology, as does the in vivo determination of enzyme activities. All these approaches are different, and it is becoming important that the appropriate approach be used for the intended purpose. Here, we therefore discuss five approaches to the measurement of enzyme activity in terms of the source of the enzyme activity, the identity of the assay medium, and the purpose of the assay.
authors.affiliation: Warsaw University of Technology, Faculty of Chemistry, Institute of Biotechnology ul.Noakowskiego 3, Warsaw, Poland.
authors.forename: Malgorzata
authors.initials: M
authors.lastname: Adamczyk
authors.forename: Karen
authors.initials: K
authors.lastname: van Eunen
authors.forename: Barbara M
authors.initials: BM
authors.lastname: Bakker
authors.forename: Hans V
authors.initials: HV
authors.lastname: Westerhoff
mesh_terms: D000465:Algorithms; D000818:Animals; D002457:Cell Extracts / Q000737:chemistry; D003470:Culture Media; D057075:Enzyme Assays / Q000379:methods*; D004798:Enzymes / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D005656:Fungal Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D049490:Systems Biology; D015003:Yeasts / Q000254:growth & development / Q000378:metabolism
chemical_list: D002457:Cell Extracts; D003470:Culture Media; D004798:Enzymes; D005656:Fungal Proteins