title: Expression and purification of catalytic domain of human macrophage elastase for high throughput inhibitor screening.
abstract: OBJECTIVE
  To obtain a catalytically active human macrophage elastase catalytic domain (hMECD) and to establish an efficient high-throughput method for screening macrophage elastase inhibitors.
  
  
  METHODS
  Catalytic domain of human macrophage elastase was expressed in E coli and characterized to establish a high-throughput screening assay using a colorimetric method. A set of 8560 pure compounds and mixtures were screened.
  
  
  RESULTS
  We have constructed an efficient E coli system for this human protein expression, and the recombinant hMECD protein was purified to homogeneity using anion-exchange chromatography after in vitro refolding from inclusion bodies. The yield of active hMECD protein was 23 mg from one liter of E coli culture after purification. Calcium and zinc ions were required both in refolding and enzymatic activity, but high concentration of zinc inhibited the refolding and activity. The hMECD cleaved several synthetic substrates including a chromogenic thiopeptolide and fluorogenic peptides with optimal activity around pH 8.0. Screening of 8560 compounds and mixtures led to identify 27 pure compounds and 14 natural products with inhibitory activity higher than 80 % at 20 mg/L.
  
  
  CONCLUSIONS
  An efficient expression and purification method for hMECD protein has been established, and the assay is effective, reliable, and fast in identifying the recombinant protein inhibitors.
authors.affiliation: National Center for Drug Screening, Institute of Materia Medica, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 201203, China. yeq@mail.shcnc.ac.cn
authors.forename: Dong-Hang
authors.initials: DH
authors.lastname: Cheng
authors.forename: Qiang
authors.initials: Q
authors.lastname: Shen
authors.forename: Jing
authors.initials: J
authors.lastname: Qian
authors.forename: Zhen
authors.initials: Z
authors.lastname: Qian
authors.forename: Qi-Zhuang
authors.initials: QZ
authors.lastname: Ye
mesh_terms: D000595:Amino Acid Sequence; D020134:Catalytic Domain; D004353:Drug Evaluation, Preclinical; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008264:Macrophages / Q000201:enzymology*; D053508:Matrix Metalloproteinase 12; D008666:Metalloendopeptidases / Q000037:antagonists & inhibitors* / Q000096:biosynthesis* / Q000302:isolation & purification; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017510:Protein Folding; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000302:isolation & purification; D017386:Sequence Homology, Amino Acid
chemical_list: D004791:Enzyme Inhibitors; D011994:Recombinant Proteins; D008666:Metalloendopeptidases; C507122:MMP12 protein, human; D053508:Matrix Metalloproteinase 12