Development of an Ultrafiltration-Liquid Chromatography/Mass Spectrometry (UF-LC/MS) Based Ligand-Binding Assay and an LC/MS Based Functional Assay for Mycobacterium tuberculosis Shikimate Kinase

作者：Mulabagal Vanisree; Calderon Angela I^*

来源：Analytical Chemistry, 2010, 82(9): 3616-3621.

DOI：10.1021/ac902849g

Shikimate kinase (SK) and other enzymes in the shikimate pathway are potential targets in the discovery of antimicrobial agents. In the current study, an ultrafiltration-liquid chromatography/mass spectrometry (UF-LC/MS) ligand based binding assay and an LC/MS based functional assay for Mycobacterium tuberculosis shikimate kinase (MtSK) were developed. Compounds 1, 2, 3, and 4 were tested for MtSK (1 mu M) at a concentration of 1 mu M. In order to evaluate the MtSK inhibitory activity, compounds 1-4 were tested at concentrations ranging from 0.05 to 1 mu M, and the enzymatic activity was assessed by quantifying shikimate-3-phosphate (S3P) by LC/MS after 60 min incubation with 2 mM shikimic acid as a substrate. The EC(50) values of compounds 1, 2, 3, and 4 were 0.30, 0.24, 0.07, and 0.18 mu M, respectively. The ligands and the S3P were analyzed using positive and negative electrospray LC/MS, respectively. The calibration curve for S3P was prepared with concentrations ranging from 4 to 125 mu g/mL, and the lower detection limit (LOD) of S3P was identified as 1.95 mu g/mL (9.75 ng on-column). This is the first application of UF-LC/MS and LC/MS in the development of ligand-binding and functional assays, respectively as a useful approach to screen MtSK inhibitors.

• 出版日期2010-5-1