"This work also has two potential applications. First, our results can be used to generate an efficient treatment for cocaine overdose. Second, the same system we describe can be engineered to detoxify chemical weapons, including sarin, soman, tabun and VX gases."
A report of the study, published online Monday (April 7) in Nature Structural Biology, presents the first crystal structure of the protein human carboxylesterase 1, or hCE1.
The protein, an enzyme, is a broad-spectrum bioscavenger found throughout the body - in the liver, small intestine, kidney, lungs, testes and scavenger cells. It also circulates to a lesser extent in human blood plasma.
In their report, Redinbo and his group describe how hCE1 is responsible for metabolizing the first step of cocaine breakdown in the body and the first two steps of heroin breakdown. The researchers determined the crystal structure of the enzyme in complexes with analogues of cocaine and heroin.
They found the enzyme could bind to two cocaine molecules simultaneously, but that it specifically generates the primary metabolic breakdown product (metabolite) of cocaine. This indicates that the enzyme holds "significant promise in the treatment of acute cocaine overdose," the report said.
"We need to engineer a more active form of the enzyme that is specific for cocaine. We can do this by generating a small number of changes in the amino acid sequence that would increase the metabolic efficiency," Redinbo said.
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Contact: Leslie H. Lang
llang@med.unc.edu
919-843-9687
University of North Carolina School of Medicine
8-Apr-2003