Comparative studies on thermoresistance of protein G-binding region and antigen determinant region of immunoglobulin G in acidic colostral whey

Abstract

The kinetics of the denaturation of antigen determinant (AGD) region and protein G-binding (PGB) region of bovine immunoglobulin G (IgG) in acidic colostral whey were studied by single radial immunodiffusion (SRID) and protein G affinity chromatography (PrGAC) during the same courses of heat treatment. The kinetic and thermodynamic parameters for heat-induced denaturation of AGD and PGB regions of IgG were determined over a temperature range of 69 Á818C. The denaturation reactions of both AGD and PGB regions of IgG were best described with apparent reaction order of 1.2, the activation energy values of the denaturation reactions were 159.42 kJ/mol and 235.37 kJ/mol respectively. This work suggested that the AGD region was more heat-labile than the PGB region of IgG in acidic colostral whey, Moreover, the higher values of the constant for the AGD region meant that, once the unfolding of the region started, denaturation would occur more quickly than the PGB region on IgG molecule. All these factors contributed to the fact that generally the IgG contents in the products of bovine colostrum determined by PrGAC would be higher than those by SRID.

Effect of heating on the distribution of transforming growth factor-β2 in bovine milk

“…Comparison of RP-HPLC profiles of milks heated from 58 to 72°C (not shown) revealed that this peak appears only at 65-68°C. It is known that bovine serum albumin (BSA) and immunoglobulin G (IgG) begins to denature beyond 60°C (Cao, Wang, & Zheng, 2007;Vermeer & Norde, 2000) and that this involves a complex sequence of unfolding and aggregation. The peak or shoulder appearing next to the large β-Lg peak might be associated with the formation of some complex involving hydrophobic interactions between β-Lg, BSA and IgG.…”

Analysis of denaturation of bovine IgG by heat and high pressure using an optical biosensor

“…Several studies have reported on the stability of bovine IgG, either in model systems or in intact milk or colostrum, to various stresses including storage, isolation and processing variables such as heat, pH and pressure (Ando et al, 2005;Cao, Wang, & Zheng, 2007;Chen & Chang, 1998;Chen, Tu, & Chang, 2000;Dominguez, Pe´rez, & Calvo, 1997;Dominguez, Pe´rez, Puyol, Sa´nchez, & Calvo, 2001;Law, 1995;Li, Bomser, & Zhang, 2005;Li et al, 2006;Li-Chan, Kummer, Losso, Kitts, & Nakai, 1995;Lindstro¨m, Paulsson, Nylander, Elofsson, & Lindmark-Ma˚nsson, 1994; Mainer, Sa´nchez, Ena, & Calvo, 1997;Ohnuki & Otani, 2005;Rosenthal, Bernstein, & Merin, 1999). These studies have utilised a range of spectroscopic, immunoassay and separation-based analytical techniques and have inevitably reported widely variable stability and reaction order estimates.…”

“…However, few studies have considered differentiation of Fab and Fc domains within bovine lacteal IgG with respect to relative conformational stability, and the potential for other milk components to moderate this stability, and conclusions remain equivocal (Cao et al, 2007;Dominguez et al, 1997Dominguez et al, , 2001Li et al, 2005;Ohnuki & Otani, 2005). A study of the stability of mouse monoclonal IgG by calorimetric and circular dichroism techniques has revealed independent denaturation transitions of Fab and Fc domains, with each region being influenced distinctively by thermal or pH stress (Vermeer & Norde, 2000).…”

Shelf life and storage stability of spray-dried bovine colostrum powders under different storage conditions

“…Thus, it is extensively suggested that immunoglobulins be added into infant formula and other foods to fortify the immunity of young children (Facon et al 1993). At present, colostrum-based products have been being industrially produced in Australia, New Zealand, USA and China, marketed as a health food supplement after standardizing their IgG content (Cao et al 2007). …”

“…For practical usage of immunoglobulins as supplements to foods, their stability under different food processing and storage conditions should be determined. Several reports have been published on stability of bovine immunoglobulins in fluid milk or bovine colostrum to homogenization, heat and ultrasonic treatments (Cao et al 2007;Fukumoto et al 1994;Li-Chan et al 1995). However, little information has been reported about stability of Igs in SDBC powder during storage.…”