Effect of heat and pH on the carbohydrate epitopes of gum from Acacia senegal recognised by monoclonal antibodies

Carbohydrate epitopes on the arabinogalactan protein (AGP) gum arabic recog nised by a panel of setter? monoclonal antibodies (MAbs), raised in a previ ous study: have been further characterised These MAbs have now been divided into three groups based on their response to mild hydrolysis and eliminati on (neutral hydrolysis) when heated in buffers at different pH values. We h ave also investigated the binding of these antibodies to three fractions of gum arabic separated by hydrophobic interaction chromatography MAb groups I and III produce consistent responses when tested against heat-treated who le and fractionated gum? arabic, whilst group II display a varied response suggesting that these MAbs recognise complex epitopes, the structure of whi ch is not immediately apparent. It appears that neutral hydrolysis is capab le of increasing or decreasing the affinity of certain epitopes, whilst hyd rolysis with a strong acid (TFA; trifluoro acetic acid) under harsh conditi ons reduces the affinity for all antigens. The results obtained have shown that the MAbs can be divided into three categories, two of which have disti nctive and easily reproducible responses to treatment of the gum and would therefore be suitable for the investigation of Acacia gums which have been subjected to food preparation procedures.