Predicting the cross-reactivities of polycyclic aromatic hydrocarbons in ELISA by regression analysis and CoMFA methods

Abstract

Immunoassays have been regarded as a possible alternative or supplement for measuring polycyclic aromatic hydrocarbons (PAHs) in the environment. Since there are too many potential cross-reactants for PAH immunoassays, it is difficult to determine all the cross-reactivities (CRs) by experimental tests. The relationship between CR and the physical-chemical properties of PAHs and related compounds was investigated using the CR data from a commercial enzyme-linked immunosorbent assay (ELISA) kit test. Two quantitative structure-activity relationship (QSAR) techniques, regression analysis and comparative molecular field analysis (CoMFA), were applied for predicting the CR of PAHs in this ELISA kit. Parabolic regression indicates that the CRs are significantly correlated with the logarithm of the partition coefficient for the octanol-water system (log K(ow)) (r(2) = 0.643, n = 23, P < 0.0001), suggesting that hydrophobic interactions play an important role in the antigen-antibody binding and the cross-reactions in this ELISA test. The CoMFA model obtained shows that the CRs of the PAHs are correlated with the 3D structure of the molecules (r(cv)(2) = 0.663, r(2) = 0.873, F(4,32) = 55.086). The contributions of the steric and electrostatic fields to CR were 40.4 and 59.6%, respectively. Both of the QSAR models satisfactorily predict the CR in this PAH immunoassay kit, and help in understanding the mechanisms of antigen-antibody interaction.

Investigating the Quantitative Structure-Activity Relationships for Antibody Recognition of Two Immunoassays for Polycyclic Aromatic Hydrocarbons by Multiple Regression Methods

“…The results of stepwise MLR, PCR and PLSR imply that S m plays an important role in affecting the CR property of the PAHs for the two ELISA kits, and 3 χ v also affects the CR for Ris C kit to some extent: $\text{For RaPID}:\text{log MCR}=1.349+0.07442\times \text{PC}1-0.7234\times \text{PC}2$ ${\text{For Ris}}^{\text{C}}:\text{log MCR}=1.178+0.002550\times \text{PC}1-0.9075\times \text{PC}2$ $\text{For RaPID}:log\text{MCR}\ast =-0.6783\times {\text{S}}_{\text{m}}\ast +1.245\times log{K}_{\text{ow}}\ast -0.6106\times (E_{\text{HOMO}}-E_{\text{LUMO}})\ast +0.2556\times {}^0\chi {}^{\text{v}\ast }-0.07527\times {}^1\chi {}^{\text{v}\ast }-0.6231\times {}^2\chi {}^{\text{v}\ast }-1.626\times {}^3\chi {}^{\text{v}\ast }$ ${\text{For Ris}}^{\text{C}}:\text{log MCR}\ast =-1.042\times {\text{S}}_{\text{m}}\ast -0.06846\times log{K}_{\text{ow}}\ast -0.1012\times (E_{\text{HOMO}}-E_{\text{LUMO}})\ast -0.1649\times {}^0\chi {}^{\text{v}\ast }-0.1778\times {}^1\chi {}^{\text{v}\ast }-0.2025\times {}^2\chi {}^{\text{v}\ast }-0.2517\times {}^3\chi {}^{\text{v}\ast }$In immunoreactions and immunoassays, the interaction between antigen and antibody is caused by the complementary spatial distribution and the strong affinity between the antigen and the antibody, such as hydrogen bonds, electrostatic interactions, van der Waals forces and hydrophobic interactions. The strong effect of S m on the CR properties of the two ELISAs reflects the important role of hydrophobic interactions in the PAH-antibody reactions, which confirms the previous result [19]. It is commonly believed that lower order mole...…”

“…Since activity data used for QSARs should be in molar dimensions, CR values were converted to molar cross-reactivity (MCR), i.e. , the ratio of the molar IC 50 of target analyte and the cross-reactant, for QSAR modeling [19]. Then, the predicted MCR was calculated by the QSAR models and converted to CR for comparison with the experimental CR value.…”

“…Then, the predicted MCR was calculated by the QSAR models and converted to CR for comparison with the experimental CR value. We assumed that the CR values “<0.5%” and “<1.6%” were low enough to describe low levels of cross-reactions in the two ELISA kit tests, and reasonably considered the CR value “<” to be “=” for regression modeling [19]. …”

“…In our previous work, we found that CR values of PAHs are significantly correlated with the data of logarithm of octanol-water partition coefficient (log K ow ), but it seemed that CR cannot be solely explained by log K ow [19]. In this article, in addition to log K ow , other six representative physicochemical, electronic and topological descriptors are selected to investigate the correlation between CR and the molecular properties of PAHs.…”

Antibody production and application for immunoassay development of environmental hormones: a review

“…In addition, the chemical structures of haptens have a great impact on the antibodies' production and their quality. Zhang et al [30] drew a conclusion that hydrophobic interactions play an important role in the antigen and antibody binding based on quantitative structureactivity relationship (QSAR) techniques, and used comparative molecular field analysis (CoMFA) to predict the cross-reactivity (CR) of the PAHs in ELISA, suggesting that haptens' steric (40.4%) and electrostatic fields (59.6%) make contributions to CR, respectively. Spier et al [31] also noted that the hydrophobic haptens would limit accessibility of the antibody, because hydrophobicity can cause conformational changes in the protein carrier and result in internalization of the hapten within hydrophobic pockets.…”