title: Evaluation of ultrasound velocity measurements for estimating protease activities using casein as substrate.
abstract: Ultrasonic resonator technology (URT) was compared with the well established UV-Vis/ninhydrin assay to estimate protease activities in defined buffer systems. Hydrolysis of casein was measured using subtilisin, trypsin, halophilic protease from Haloferax mediterranei and Bacillus lentus alkaline protease. Sensitivity, reproducibility, working range as well as the limit of detection and the limit of quantification were comparable for both methods. Salt concentrations (0.5 M NaCl) interfered with the URT method. The quantification of protease activity by URT was possible when the product concentration measured by the UV-Vis/ninhydrin assay was correlated to the corresponding ultrasonic velocity signals.
authors.affiliation: TF Instruments GmbH, 69120 Heidelberg, Germany.
authors.forename: Karin
authors.initials: K
authors.lastname: Born
authors.forename: Anja
authors.initials: A
authors.lastname: Manns
authors.forename: Kristina
authors.initials: K
authors.lastname: Dzeyk
authors.forename: Sabine
authors.initials: S
authors.lastname: Lutz-Wahl
authors.forename: Daniel
authors.initials: D
authors.lastname: Gau
authors.forename: Lutz
authors.initials: L
authors.lastname: Fischer
mesh_terms: D000465:Algorithms; D002364:Caseins / Q000737:chemistry*; D002623:Chemistry Techniques, Analytical / Q000379:methods*; D004789:Enzyme Activation; D010447:Peptide Hydrolases / Q000032:analysis* / Q000737:chemistry*; D013010:Sonication / Q000379:methods*
chemical_list: D002364:Caseins; D010447:Peptide Hydrolases