Pepsin-mediated hydrolysis of partially purified chicken serum immunoglobulin Y under acidic conditions: A preliminary study using SDS-PAGE

Immunoglobulin Y (IgY) is a poultry antibody platform useful for biological and biomedical applications, but its electrophoretic response to acid proteolysis depends on digestion conditions and sample preparation. This preliminary study evaluated bovine pepsin-mediated hydrolysis of partially purified IgY from local Indonesian chicken serum. IgY was partially isolated using caprylic acid treatment followed by ammonium sulphate precipitation, quantified at 280 nm and adjusted to 1 mg/mL, and incubated with bovine pepsin at pH 2.0–2.5, 37°C for 30, 60, or 90 minutes. The reaction was stopped by rapid neutralisation using 1 M Tris and heating at 95°C for 3 minutes. The product was analysed by 12.5% SDS-PAGE using 5x Laemmli sample buffer containing beta-mercaptoethanol (BME). The pepsin-free control retained the main bands at approximately 100–135 kDa and 48–63 kDa, whereas the pepsin-treated samples showed a prominent band around 68–75 kDa with decreasing intensity over time and the loss of the band around 125–135 kDa. These findings indicate that bovine pepsin alters the SDS-PAGE profile of partially purified chicken serum IgY under acidic conditions. Further confirmation via densitometry, immunochemistry, or proteomics is recommended.