Advanced Biocatalysts Based on Hexahistidine-Containing Organophosphorus Hydrolase for Chemical and Biological Defense

Abstract

The advanced biocatalysts based on hexahistidine-tagged organophosphorus hydrolase (His6-OPH) were recently developed for the detoxification of various organophosphorus compounds and degradation of N-acyl homoserine lactones. Due to enzyme immobilization, some of obtained biocatalysts are quite stable, easy to use and very effective/active (e.g. tens of millions of substrate solution volumes appeared to be treated with column cartridges containing immobilized His6-OPH). Recently, the possible bioengineering of different stabilized nanocomplexes of His6-OPH due to its non-covalent binding with different compounds (polymers, antioxidants, antimicrobials, etc.) was demonstrated. Firstly, it was realized by computer modeling via molecular docking. Polymers of amino acids (polyglutamic and polyasparctic acids) were established to be the most effective stabilizers of the enzyme that enabled effective preservation of the enzyme activity. Up to 100 %-retention of initial catalytic characteristics of the enzyme was reached in obtained enzymatic complexes. Such nanobiocatalysts were stabilized against inactivating effects of solvents, temperatures and were able to circulate in vivo for at least 25 hours. It appeared that different antioxidants can be applied as partners of the enzyme in the nanocomplexing. Thus, a new set of original enzymatic antidotes were developed possessing dual action: both hydrolytic activity against organophosphorus neurotoxins and improved antioxidant activity. Additionally, it was shown that different organophosphorus compounds and N-acyl homoserine lactones could be molecularly docked directly to the active centers of His6-OPH dimer, thus allowing to theoretically clarify some new prospective substrates for the enzymatic hydrolysis. It appeared that new type of nanocomplexes of the enzyme with antibiotics also can be prepared. In this case the combination of antibiotics with enzyme quenching the quorum of the pathogenic gram-negative bacteria was performed. The enzyme being stabilized by the various antibiotics (especially those containing β-lactame ring) played the role of a carrier for the antimicrobial compounds significantly improving their efficiency of the action. Such biocatalysts and/or method of their design have a great potential and can be very useful for both chemical and biological defense.

Keywords

• antibiotics
• antioxidants
• hydrolysis
• n-acyl homoserine lactones
• nanocomplexes
• organophosphorous hydrolase
• organophosphorus compounds