title: Microcalorimetric methods for substrate determination in flow systems with immobilized enzymes.
abstract: The enthalpy of processes catalyzed by immobilized enzymes in the reaction cell of a LKB-flow calorimeter is used for determination of urea (0.5-5 mumol) and glucose (0.03-0.5 mumol). Accuracy is 2-5% and the time needed for one analysis is 20 min. A sensitive "enzyme thermistor" consisting of a flow through cell with an immobilized enzyme and two thermistors is described, which permits glucose determinations (0.05-1 mumol +/- 0.03 mumol) by means of temperature difference caused by reaction heat. Coupling of enzyme reactions for increasing reaction heat and consequently sensitivity in calorimetric determinations is demonstrated.
mesh_terms: D001665:Binding Sites; D002151:Calorimetry; D002374:Catalase; D004798:Enzymes / Q000378:metabolism*; D005947:Glucose / Q000032:analysis; D005949:Glucose Oxidase / Q000378:metabolism; D008722:Methods; D011485:Protein Binding; D013816:Thermodynamics; D014508:Urea / Q000032:analysis; D014510:Urease / Q000378:metabolism
chemical_list: D004798:Enzymes; D014508:Urea; D005949:Glucose Oxidase; D002374:Catalase; D014510:Urease; D005947:Glucose