Effect of chlorine atoms on inhibition effect between amide herbicides and urease enzyme: molecular mechanism and structure-activity relationship.

Abstract

Amide herbicides (AHs) were disturbed urease (UA) activity and soil microbial community, caused soil nutrient changes. Activity of UA was inhibited by AHs via groups of chlorine, benzene ring, peptide bond (-N-/-CO-). Difference of surface charge distribution were mainly derived from position to connected -Cl, distance of -O- from ether group and -N from peptide bond, difference of structure/length for hydrocarbon chain, and different regions of negative charge enrichment. Developmental toxicity (DT) for alachlor was strongest related to smaller structure and weaker steric hindrance effect, mutagenicity for propanil was weakest could be related to missing ether group. Molecular mechanism and structural activity relationship for inhibition of AHs and UA based on functional groups, amino acids with high frequency, hydrogen bonds, hydrophobic interactions, binding area (BA) of butachlor (396.3 Å2), absolute value of binding energy (|BE|) of propanil (2.93 kJ/mol) (which as highest), quantitative structural relationship between BA and |BE|, which was negative correlation. BA for AHs and UA had negatively correlation for density with correlation coefficient (r) as -0.937 (p ≤ 0.01). |BE| for AHs and UA had positively correlation for density with r as 0.847 (p ≤ 0.05), and negatively correlation for molecular weight (MW) with r as -0.973 (p ≤ 0.001). Results provided technological support and theoretical foundation for toxic effects of SEs activity, health effects, risk regulation and control of AHs.