title: Reversible detection of proteases and their inhibitors by a pulsed chronopotentiometric polyion-sensitive electrode.
abstract: Polymer membrane electrodes operated by pulsed chronopotentiometry have recently been introduced to replace traditional ion-selective electrodes for a number of applications. While ion-selective electrodes for the polycation protamine have been reported, for instance, a pulsed chronopotentiometric readout mode (called here pulstrode) provides improved stability and reproducibility while exhibiting sufficient selectivity for the direct detection of protamine in undiluted whole blood samples. Here, such protamine-sensitive pulstrodes are applied for the real-time detection of the activity of the protease trypsin and its soybean inhibitor. This is possible because small fragments produced by the trypsin digestion are not detectable by the protamine-sensing membrane. The real-time response to the proteolytic reaction is shown to exhibit good reproducibility and reversibility, and the initial reaction rate is dependent on the concentration of the protease and its inhibitor.
authors.affiliation: Department of Chemistry, Purdue University, IN 47907, USA.
authors.forename: Yida
authors.initials: Y
authors.lastname: Xu
authors.forename: Alexey
authors.initials: A
authors.lastname: Shvarev
authors.forename: Sergey
authors.initials: S
authors.lastname: Makarychev-Mikhailov
authors.forename: Eric
authors.initials: E
authors.lastname: Bakker
mesh_terms: D004566:Electrodes; D007700:Kinetics; D009282:Naphthalenesulfonates / Q000737:chemistry; D011199:Potentiometry / Q000379:methods*; D011479:Protamines / Q000378:metabolism; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013997:Time Factors; D014357:Trypsin / Q000032:analysis* / Q000378:metabolism*; D014361:Trypsin Inhibitors / Q000032:analysis* / Q000494:pharmacology*
chemical_list: D009282:Naphthalenesulfonates; D011479:Protamines; D000644:Quaternary Ammonium Compounds; D014361:Trypsin Inhibitors; D014357:Trypsin