Comparative Study on Kinetics of Nonenzymatic Deamidation of Soy Protein and Egg White Lysozyme

The kinetics of the deamidation reactions of soy protein and lysozyme followed an apparent first-order reaction. The deamidation rate for lysozyme at pHs above 5 was higher than that of soy protein. This may be because lysozyme has more Asn than Gln, while soy protein has more Gln than Asn. At pH 3, there was not much difference between the two proteins regarding their deamidation rates. This suggested that protein deamidation for both proteins may be more structurally sensitive at neutral or base conditions due to a succinimide formation mechanism. Under acidic conditions, it was believed that the deamidation of both proteins went via a direct hydrolysis pathway