Butyrylcholinesterase variants and methods of use

Abstract

The invention provides four butyrylcholinesterase variants having increased cocaine hydrolysis activity as well as the corresponding encoding nucleic acids. The invention also provides libraries comprising butyrylcholinesterase variants having at least one amino acid alteration in one or more regions of butyrylcholinesterase and further having at least one butyrylcholinesterase variant exhibiting enhanced cocaine hydrolysis activity compared to butyrylcholinesterase. The invention further provides methods of hydrolyzing a cocaine-based butyrylcholinesterase substrate as well as methods of treating a cocaine-induced condition.

Description

[0001] This invention was made with government support under grant number 1R01 DA011707 awarded by the National Institutes of Health. The United States Government has certain rights in this invention.BACKGROUND OF THE INVENTION [0002] This invention relates to butyrylcholinesterase variants and, more specifically to the production and therapeutic use thereof. [0003] Cocaine abuse is a significant social and medical problem in the United States as evidenced by the estimated 3.6 million chronic users. Cocaine abuse often, leads to long-term dependency as well as life-threatening overdoses. However, no effective antagonist is currently available that combats the reinforcing and toxic effects of cocaine. [0004] One difficulty in identifying an antagonist to treat cocaine abuse arises largely from the narcotic's mechanism of action. Specifically, cocaine inhibits the re-uptake of neurotransmitters resulting in overstimulation of the reward pathway. It is this overstimulation that is prop...

AI Technical Summary

Benefits of technology

[0011] The invention provides four butyrylcholinesterase variants having increased cocaine hydrolysis activity as well as the corresponding encoding nucleic acids. The invention also provides libraries comprising butyrylcholinesterase variants having at least one amino acid alteration in one or more regions of butyrylcholinesterase and further having at least one butyrylcholinesterase variant exhibiting enhanced cocaine hydrolysis activity compared to butyrylcholinesterase. The invention further provides methods of hydrolyzing a cocaine-based butyrylcholinesterase substrate as well as methods of treating a cocaine-induced condition.

Problems solved by technology

Cocaine abuse is a significant social and medical problem in the United States as evidenced by the estimated 3.6 million chronic users.

Cocaine abuse often, leads to long-term dependency as well as life-threatening overdoses.

However, no effective antagonist is currently available that combats the reinforcing and toxic effects of cocaine.

One difficulty in identifying an antagonist to treat cocaine abuse arises largely from the narcotic's mechanism of action.

Specifically, cocaine inhibits the re-uptake of neurotransmitters resulting in overstimulation of the reward pathway.

In addition, at higher concentrations, cocaine interacts with multiple receptors in both the central nervous and cardiovascular systems, leading to toxicities associated with overdose.

Because of this multifarious mechanism of action of cocaine, it is difficult to identify selective antagonists to treat both the reinforcing and toxic effects of cocaine.

Additionally, antagonists that block cocaine's binding to its receptors tend to display many of the same deleterious effects as cocaine.

In addition, these dopamine antagonists produce profound decreases in other behaviors when the doses are increased only slightly above the levels that display an effect on cocaine self-administration behavior.

Therefore, it has been suggested that individuals with defective versions of the butyrylcholinesterase gene are at higher risk for life-threatening reactions to cocaine.

Recently, administration of butyrylcholinesterase has been demonstrated to confer limited protection against cocaine overdose in mice and rats.

Although administration of butyrylcholinesterase provides some effect against cocaine toxicity in vivo, it is not an efficient catalyst of cocaine hydrolysis.

The low cocaine hydrolysis activity of wild-type butyrylcholinesterase requires the use of prohibitively large quantities of purified enzyme for therapy.

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