Analysis of trypsin activity at β-casein layers formed on hydrophobic surfaces using a multiharmonic acoustic method

Abstract

Proteolysis of milk proteins, such as caseins, caused by milk proteases, can change the organoleptic and nutritional characteristics of milk, and therefore it is essential to monitor this enzymatic activity....

Application of Multiharmonic QCM-D for Detection of Plasmin at Hydrophobic Surfaces Modified by β-Casein

“…Following incubation of β-casein with plasmin, the adlayer undergoes mass loss (phase 5), and the harmonics tend to converge (overlap), except for the fundamental frequency, which does not show the same trend. This result agrees with our recently published data on the cleavage of β-casein by trypsin [23]. The overshoot at the beginning of the adlayer formation has already been observed and explained in other works [34,35].…”

“…Therefore, analysis of the changes in the frequency and dissipation is also important for the study of the viscoelastic properties of the organic layers at the crystal surface contacted with aqueous solution. Most recently we applied multiharmonic analysis of viscoelastic properties of β-casein layers following cleavage by trypsin [23]. This analysis has been based on a Voinova-Voigt model using following equations [21,22]:…”

“…The Sauerbrey Equation (1) allows calculation of the mass deposited on the QCM crystal and its portion removed due to the plasmin cleavage. The details of data analysis can be found in our recent publication focused on trypsin detection [23]. Here we will focus on the analysis of viscoelastic properties of the β-casein layers by plasmin cleavage.…”

“…Moreover, using the Voinova-Voigt viscoelastic model [21,22], it was possible to quantify the variations of viscoelastic parameters during plasmin cleavage and to describe the architecture of the β-casein layer. The viscoelastic properties of β-casein layers following plasmin cleavage were compared with those caused by trypsin using the results of a recently published paper [23].…”

Detection of Gingipain Activity Using Solid State Nanopore Sensors

“…Michaelis-Menten model was used to estimate the apparent Michaelis-Menten constant K M ′ (9.41 nM). This value is higher than the one found in the literature (0.38 nM) [27], which can be explained by the shape and size of the nanopore, resulting in steric hinderance that reduce accessibility and the rate of the enzymatic reaction.…”