Influence of Alcalase and transglutaminase on immunoreactivity of cow milk whey proteins

The aim of the research was to determine the changes in the immunoreactivity of whey protein concentrate (WPC) modified by two enzymes: proteinase, Alcalase 2.4L FG (Novo Nordisk), and cross-linked transglutaminase (EC 2.3.2.13, Activa (TM) P, m-TG, Ajinomoto). The new products were characterised by 2D electrophoresis, immunoblotting, and ELISA methods. The WPC hydrolysate obtained with Alcalase contained proteins and peptides characterised mostly by low molecular weight peptides (MW < 14.4 kDa) in the pH range of 3-10, Immunoblotting showed strong immunoreactive properties of the hydrolysate with alpha-Ia and beta-Ig polyclonal rabbit antibodies. The 2D electrophoretic patterns of WPC and its modified product obtained with m-TG did no differ significantly. However, the immunoblot analysis demonstrated that WPC showed a stronger reactivity towards IgE of allergic patients as compared to WPC with m-TG. ELISA methods showed that two-step hydrolysis with Alcalase followed by m-TG significantly reduced the immunoreactive properties of whey proteins. No cross reactions were observed with alpha-Ia and only about 0.6% cross-reactivity with beta-Ig.