Submitted to: Analytica Chimica Acta
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/18/2009
Publication Date: 5/25/2009
Citation: Xu, Z., Xie, G., Li, Y., Wang, B., Beier, R.C., Lei, H., Wang, H., Shen, Y., Sun, Y. 2009. Production and characterization of a broad-specificity polyclonal antibody for O,O-diethyl organophosphorus pesticides and a quantitative structure-activity relationship study of antibody recognition. Analytica Chimica Acta. 647:90-96.
Interpretive Summary: Organophosphorus pesticides (OPs) have been widely used in agricultural and domestic applications for more than six decades. However, OP intoxication can occur in humans and animals. We have developed antibodies that recognize a broad group of seven commonly used OPs. Antibodies are substances that are produced by the immune system in response to foreign substances which enter the body. Once the antibodies to a foreign substance are isolated, they can be used in a method to detect the presence of that foreign substance. The antibodies that we isolated may be used in an easy-to-use test called an enzyme-linked imunosorbent assay or ELISA for the detection of OPs. Also, a computer model was constructed using molecular parameters of the OPs tested to help study how the antibody recognized the OPs. The model gave good correlation between the observed data and calculated values.
Technical Abstract: Polyclonal antibody (PAb) with broad-specificity for O,O-diethyl organophosphorus pesticides (OPs) against a generic hapten, 4-(diethoxyphosphoro thioyloxy) benzoic acid, was produced. The obtained PAb showed high sensitivity to seven commonly used O,O-diethyl OPs in a competitive indirect enzyme-linked immunosorbent assay (ciELISA) using a heterologous coating antigen, 4-(3-(diethoxyphosphorothioyloxy)phenylamino)-4-oxobutanoic acid. The 50% inhibition value (IC50) was 348 ng mL–1 for parathion, 13 ng mL–1 for coumaphos, 22 ng mL–1 for quinalphos, 35 ng mL–1 for triazophos, 751 ng mL–1 for phorate, 850 ng mL–1 for dichlofenthion, and 1301 ng mL–1 for phoxim. The limit of detection (LOD) met the ideal detection criteria of all the seven OP residues. A quantitative structure-activity relationship (QSAR) model was constructed to study the mechanism of antibody recognition using multiple linear regression analysis. The results indicated that the frontier-orbital energies (energy of the highest occupied molecular orbital, EHOMO, and energy of the lowest unoccupied molecular orbital, ELUMO) and hydrophobicity (log of the octanol/water partition coefficient, logP) were mainly responsible for the antibody recognition. The linear equation was log(IC50) = – 63.055EHOMO + 16.112ELUMO + 0.589LogP – 25.584, with a determination coefficient (r**2) of 0.906.