Wild-type and A328W mutant human butyrylcholinesterase tetramers expressed in Chinese hamster ovary cells have a 16-hour half-life in the circulation and protect mice from cocaine toxicity.
Human butyrylcholinesterase (BChE) hydrolyzes cocaine to inactive metabolites. A mutant of human BChE, A328W, hydrolyzed cocaine 15-fold faster compared with wild-type BChE. Although the catalytic properties of human BChE secreted by Chinese hamster ovary (CHO) cells are identical to those of native BChE, a major difference became evident when the recombinant BChE was injected into rats and mice. Recombinant BChE disappeared from the circulation within minutes, whereas native BChE stayed in the blood for a week. Nondenaturing gel electrophoresis showed that the recombinant BChE consisted mainly of monomers and dimers. In contrast, native BChE is a tetramer. The problem of the short residence time was solved by finding a method to assemble the recombinant BChE into tetramers. Coexpression in CHO cells of BChE and 45 residues from the N terminus of the COLQ protein yielded 70% tetrameric BChE. The resulting purified recombinant BChE tetramers had a half-life of 16 h in the circulation of rats and mice. The 16-h half-life was achieved without modifying the carbohydrate content of recombinant BChE. The protective effect of recombinant wild-type and A328W mutant BChE against cocaine toxicity was tested by measuring locomotor activity in mice. Pretreatment with wild-type BChE or A328W tetramers at a dose of 2.8 units/g i.p. reduced cocaine-induced locomotor activity by 50 and 80%. These results indicate that recombinant human BChE could be useful for treating cocaine toxicity in humans.
Eppley Institute, University of Nebraska Medical Center, 986806 Nebraska Medical Center, Omaha, NE 68198-6805, USA.
Ellen G
EG
Duysen
Cynthia F
CF
Bartels
Oksana
O
Lockridge
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D001483:Base Sequence; D002091:Butyrylcholinesterase / Q000235:genetics / Q000378:metabolism* / Q000493:pharmacokinetics; D016466:CHO Cells; D003042:Cocaine / Q000493:pharmacokinetics / Q000633:toxicity*; D006224:Cricetinae; D006207:Half-Life; D006801:Humans; D007700:Kinetics; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010446:Peptide Fragments / Q000737:chemistry; D011994:Recombinant Proteins / Q000378:metabolism / Q000493:pharmacokinetics; D013379:Substrate Specificity
D010446:Peptide Fragments; D011994:Recombinant Proteins; D002091:Butyrylcholinesterase; D003042:Cocaine