Inmunochemical Study of Soybean Proteins that Cross React whit Cow’s Milk Proteins

LAREU, FABRICIO; DOCENA, GUILLERMO; PETRUCCELLI, SILVANA

Puerto Iguazú

Simposio; Protein Phosphorylation and Biorregulation” de Sociedad Argentina de Bioquímica y Biología Molecular (SAIB); 2004

Sociedad Argentina de Bioquímica y Biología Molecular (SAIB)

Soy based formulas are used as milk substitute for cows´ milk allergic (CMA) infants because are cheaper and more palatable than other hydrolyzed formulas. Approximately, 10% to 35% of CMPA infants do not tolerate soy proteins during the treatment. Identification of cross-reactive proteins will give valuable information to develop soy based hypoallergenic substitutes. We have identified glycinin A4A5B3 as one of the proteins that cross-reacts with cows’ milk proteins. The aim of this work was to analyze the in vitro cross reactivity of a soybean variety (Raiden) that naturally lacks A4A5B3. Soy proteins obtained from both conventional and Raiden seeds and recombinant glycinin A2B1a, A4A5B3 and a subunit b-conglycinin were used in this study. Cross-reactive proteins were analyzed by ELISA and Western Blot using a CMP-specific rabbit polyclonal antiserum and three monoclonal antibodies (mAb) with high specificity for a- (1D5), b- (2A1) and k-casein (3B5). Conventional soybean has only one protein of 23kDa that showed reactivity with the anti-milk polyclonal serum and four proteins (23, 37, 53 and 57kDa) that showed strong reactivity with the mAbs 2A1 and 3B5. In contrast, Raiden has only one protein (57kDa) that cross reacts with CMP; and it was identified as aa’-b-conglycinin using soybean purified and recombinant aa’subunits. MAbs 2A1 and 3B5 showed reactivity against recombinant A4A5B3 while mAb 1D5-I did not. This results confirm the cross reactivity of A4A5B3 with CMP and open the possibility of use of Raiden as cow milk substitute.