Binding affinity and adhesion force of organophosphate hydrolase enzyme with soil particles related to the isoelectric point of the enzyme

• Published in: Ecotoxicology and environmental safety Vol. 141; pp. 85 - 92
• Main Authors: Islam, Shah Md. Asraful, Yeasmin, Shabina, Islam, Md. Saiful, Islam, Md. Shariful
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 01-07-2017
• Subjects: Adhesion force; Environmental Restoration and Remediation; Green Fluorescent Proteins - genetics; Histidine - genetics; Isoelectric Point; Microscopy, Atomic Force; Models, Molecular; Mutagenesis, Site-Directed; Mutation; Organophosphate hydrolase enzyme; Organophosphate pesticide; Organophosphates - chemistry; Pesticide Residues - chemistry; Phosphoric Monoester Hydrolases - chemistry; Phosphoric Monoester Hydrolases - genetics; Phosphoric Monoester Hydrolases - metabolism; Protein Binding; Pseudomonas - enzymology; Pseudomonas - genetics; Soil - chemistry; Soil binding; Soil Pollutants - chemistry; Spectroscopy, Fourier Transform Infrared; Substrate Specificity; Adhesion force; Mutation; Soil binding; Organophosphate hydrolase enzyme; Organophosphate pesticide
• ISSN: 0147-6513; 1090-2414
• DOI: 10.1016/j.ecoenv.2017.03.010

The binding affinity of organophosphate hydrolase enzyme (OphB) with soil particles in relation to the isoelectric point (pI) was studied. Immobilization of OphB with soil particles was observed by confocal microscopy, Fourier transform infrared spectroscopy (FT-IR), and Atomic force microscopy (AFM). The calculated pI of OphB enzyme was increased from 8.69 to 8.89, 9.04 and 9.16 by the single, double and triple mutant of OphB enzyme, respectively through the replacement of negatively charged aspartate with positively charged histidine. Practically, the binding affinity was increased to 5.30%, 11.50%, and 16.80% for single, double and triple mutants, respectively. In contrast, enzyme activity of OphB did not change by the mutation of the enzyme. On the other hand, adhesion forces were gradually increased for wild type OphB enzyme (90 pN) to 96, 100 and 104 pN for single, double and triple mutants of OphB enzyme, respectively. There was an increasing trend of binding affinity and adhesion force by the increase of isoelectric point (pI) of OphB enzyme.
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•The organophosphate hydrolase enzyme (OphB) is capable to bind with soil particles.•The binding ability of OphB enzyme with soil particles depends on isoelectric point.•Increasing trend of adhesion force observed by the increase of pI of OphB enzyme.