From Proteopediaproteopedia link
Crystal Structure of Human Liver Carboxylesterase complexed to Etyl Acetate; A Fatty Acid Ethyl Ester Analogue
[EST1_HUMAN] Involved in the detoxification of xenobiotics and in the activation of ester and amide prodrugs. Hydrolyzes aromatic and aliphatic esters, but has no catalytic activity toward amides or a fatty acyl-CoA ester. Hydrolyzes the methyl ester group of cocaine to form benzoylecgonine. Catalyzes the transesterification of cocaine to form cocaethylene. Displays fatty acid ethyl ester synthase activity, catalyzing the ethyl esterification of oleic acid to ethyloleate. 
Publication Abstract from PubMed
Human carboxylesterase 1 (hCE1) exhibits broad substrate specificity and is involved in xenobiotic processing and endobiotic metabolism. We present and analyze crystal structures of hCE1 in complexes with the cholesterol-lowering drug mevastatin, the breast cancer drug tamoxifen, the fatty acyl ethyl ester (FAEE) analogue ethyl acetate, and the novel hCE1 inhibitor benzil. We find that mevastatin does not appear to be a substrate for hCE1, and instead acts as a partially non-competitive inhibitor of the enzyme. Similarly, we show that tamoxifen is a low micromolar, partially non-competitive inhibitor of hCE1. Further, we describe the structural basis for the inhibition of hCE1 by the nanomolar-affinity dione benzil, which acts by forming both covalent and non-covalent complexes with the enzyme. Our results provide detailed insights into the catalytic and non-catalytic processing of small molecules by hCE1, and suggest that the efficacy of clinical drugs may be modulated by targeted hCE1 inhibitors.
Structural insights into drug processing by human carboxylesterase 1: tamoxifen, mevastatin, and inhibition by benzil.,Fleming CD, Bencharit S, Edwards CC, Hyatt JL, Tsurkan L, Bai F, Fraga C, Morton CL, Howard-Williams EL, Potter PM, Redinbo MR J Mol Biol. 2005 Sep 9;352(1):165-77. PMID:16081098
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.