Biomedical Research

Mycobacterium tuberculosis is known to secrete number of proteins which play an important role in pathogenicity and diagnosis. A diagnostically important secreted antigen, Excretory Secretory-31 (SEVA TB ES-31) protein with serine protease activity was isolated from Mycobacterium tuberculosis H37Ra culture filtrate. Serine proteases like Chymotrypsin have been reported to possess lipase activ-ity as the catalytic triad is similar in serine protease and some lipase enzymes. In this study, ES-31 showed presence of 44.5U/mg pr of lipase activity by titrimetric assay. The lipase activity was inhib-ited by lipase inhibitor, Orlistat by 100%, as well as by serine metalloprotease inhibitors, Phenyl me-thyl sulphonyl fluoride and Ethylene Diamine Tetraacetic acid by 100%. The serine protease activity of ES-31 was inhibited by Phenyl methyl sulphonyl fluoride, Ethylene Diamine Tetraacetic acid, and orlistat by 78.3%, 64.3%, 89.4% respectively. Inhibition of serine protease activity of ES-31 by lipase inhibitor and inhibition of lipase activity of ES-31 by serine protease inhibitor suggests that the cata-lytic site of ES-31 is sensitive to both types of the inhibitors and ES-31 may be a chymotrypsin-like protein with drug target potential

Author(s): Gauri Wankhade, Anindita Majumdar, Pranita D Kamble, BC Harinath
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