TY - JOUR
T1 - In vitro characterization of cationic copolymer-complexed recombinant human butyrylcholinesterase
AU - Pope, Carey
AU - Uchea, Chibuzor
AU - Flynn, Nicholas
AU - Poindexter, Kirstin
AU - Geng, Liyi
AU - Brimijoin, W. Stephen
AU - Hartson, Steve
AU - Ranjan, Ashish
AU - Ramsey, Joshua D.
AU - Liu, Jing
N1 - Publisher Copyright:
© 2015 Elsevier Inc. All rights reserved.
PY - 2015/12/1
Y1 - 2015/12/1
N2 - Effective use of exogenous human BChE as a bioscavenger for organophosphorus toxicants (OPs) is hindered by its limited availability and rapid clearance. Complexes made from recombinant human BChE (rhBChE) and copolymers may be useful in addressing these problems. We used in vitro approaches to compare enzyme activity, sensitivity to inhibition, stability and bioscavenging capacity of free enzyme and copolymer-rhBChE complexes (C-BCs) based on one of nine different copolymers, from combinations of three molecular weights (MW) of poly-l-lysine (PLL; high MW, 30-70 kDa; medium MW, 15-30 kDa; low MW, 4-15 kDa) and three grafting ratios of poly(ethylene glycol) (PEG; 2:1, 10:1, 20:1). Retarded protein migration into acrylamide gels stained for BChE activity was noted with all copolymers as the copolymer-to-protein ratio was increased. BChE activity of C-BCs was lower relative to free enzyme, with the 2:1 grafting ratio showing generally greater reduction. Free enzyme and C-BCs showed relatively similar in vitro sensitivity to inhibition by paraoxon, but use of the 20:1 grafting ratio led to lower potencies. Through these screening assays we selected three C-BCs (high, medium and low MW; 10:1 grafting) for further characterizations. BChE activity was higher in C-BCs made with the medium and low compared to high MW-based copolymer. C-BCs generally showed higher stability than free enzyme when maintained for long periods at 37 °C or following incubation with chymotrypsin. Free enzyme and C-BCs were similarly effective at inactivating paraoxon in vitro. While these results are promising for further development, additional studies are needed to evaluate in vivo performance.
AB - Effective use of exogenous human BChE as a bioscavenger for organophosphorus toxicants (OPs) is hindered by its limited availability and rapid clearance. Complexes made from recombinant human BChE (rhBChE) and copolymers may be useful in addressing these problems. We used in vitro approaches to compare enzyme activity, sensitivity to inhibition, stability and bioscavenging capacity of free enzyme and copolymer-rhBChE complexes (C-BCs) based on one of nine different copolymers, from combinations of three molecular weights (MW) of poly-l-lysine (PLL; high MW, 30-70 kDa; medium MW, 15-30 kDa; low MW, 4-15 kDa) and three grafting ratios of poly(ethylene glycol) (PEG; 2:1, 10:1, 20:1). Retarded protein migration into acrylamide gels stained for BChE activity was noted with all copolymers as the copolymer-to-protein ratio was increased. BChE activity of C-BCs was lower relative to free enzyme, with the 2:1 grafting ratio showing generally greater reduction. Free enzyme and C-BCs showed relatively similar in vitro sensitivity to inhibition by paraoxon, but use of the 20:1 grafting ratio led to lower potencies. Through these screening assays we selected three C-BCs (high, medium and low MW; 10:1 grafting) for further characterizations. BChE activity was higher in C-BCs made with the medium and low compared to high MW-based copolymer. C-BCs generally showed higher stability than free enzyme when maintained for long periods at 37 °C or following incubation with chymotrypsin. Free enzyme and C-BCs were similarly effective at inactivating paraoxon in vitro. While these results are promising for further development, additional studies are needed to evaluate in vivo performance.
KW - Bioscavenger
KW - Nerve agent
KW - Organophosphate
KW - Paraoxon
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U2 - 10.1016/j.bcp.2015.10.005
DO - 10.1016/j.bcp.2015.10.005
M3 - Article
C2 - 26456723
AN - SCOPUS:84946567797
SN - 0006-2952
VL - 98
SP - 531
EP - 539
JO - Biochemical Pharmacology
JF - Biochemical Pharmacology
IS - 3
ER -