engleski

Inhibition of extracellular lipase from Streptomyces rimosus by three distinctive serine specific agents

A novel GDS(L) lipase (EC 3.1.1.3) from Streptomyces rimosus R6-554W was purified and biochemically characterized ; cloning and high level expression of its gene were described and sequence was deduced by bioinformatic approach. The mass spectrometry with MALDI-TOF and MALDI-QIT-RTOF were used to characterize wild-type and overexpressed lipase (SrL). The molecular mass was determined, 24165.76 Da. The intramolecular disulfide bonds C27-C52, C93-C101 and C151-C198 were determined. To stabilize SrL a few complexes with the inhibitors were prepared and crystallization experiments are in due course. In order to examine the inhibitor activity of our novel lipase we tested 3, 4-dichloroisocoumarin (DCI) - typical inhibitor for serine proteases, and tetrahydrolipstatin (THL) - a pancreatic lipase inhibitor ; the experiments with 1-O-hexadecyl-2-O-perylenedodecyl-sn-glycero-3-phosphonic acid-(n-hexyl)-p-nitrophenyl ester - a characteristic lipase inhibitor are initiated. DCI and THL both inactivated Streptomyces rimosus lipase. DCI (30-fold molar excess) almost completely inhibited SrL already after 15 min of incubation. However, nearly total inhibition of SrL with THL (5560-fold molar excess) was obtained only after 24 h incubation in the presence of 50% 2-propanol. The inactivation kinetics of SrL by THL and DCI was monitored and kinetic parameters were determined. DCI-inhibited Streptomyces rimosus lipase was analyzed with mass spectrometry. MALDI-MS of intact SrL-DCI complex showed one inhibitor molecule bound per lipase molecule.

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