PMSF
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Intracellular proteolytic activities of B. megaterium KM occur soluble in the cytoplasm and periplasm and insoluble in the membrane. Two proteolytic enzymes were found in the cytoplasmic fraction by gel filtration on Sephadex G 150 and by polyacrylamide gel electrophoresis. The first enzyme called CI was stable, had a relative molecular mass of Mr = 105,000 (M = 105 kg/mol) and was inhibited by EDTA and PMSF, whereas the second, designated CII, was labile and had a relative molecular mass of Mr = 46,000 (M = 46 kg/mol). Because of its lability it could not be characterized in detail. In the "periplasm" only a single proteolytic enzyme P (Mr = 28,000; M = 28 kg/mol) inhibited by EDTA could be demonstrated. The extracellular enzyme exhibited similar properties. The membrane proteolytic activity was sensitive to PMSF and EDTA. The membrane enzymes have not yet been solubilized. In cells of the mutant KM 12 that does not produce the extracellular proteinase, only one type of proteinase, in all its properties identical with the cytoplasmic proteinase CI, could be demonstrated.
The Candida haemulonii complex (Candida haemulonii, Candida haemulonii var. vulnera, and Candida duobushaemulonii) comprises emerging opportunistic human fungal pathogens with recognized multidrug-resistance profiles. Little is known about the virulence markers produced by this fungal complex. However, it is recognized that Candida spp. express a large array of peptidases, which play multiple roles in different aspects of fungal-host interactions. In the present study, we have identified proteolytic enzymes in clinical isolates of the C. haemulonii complex using zymographic assays. Peptidases able to hydrolyze gelatin, casein, albumin, hemoglobin, and immunoglobulin G were detected in cell-free supernatants and cellular extracts taken from the three species forming the C. haemulonii complex. Overall, peptidases were preferentially evidenced at physiological pH and temperatures of 37-42 °C, with molar masses between 35 and 85 kDa. Peptidase profiles of C. haemulonii and C. haemulonii var. vulnera isolates were quite similar, contrasting to the peptidases produced by C. duobushaemulonii. Almost all peptidases were inhibited by phenylmethanesulfonyl fluoride (PMSF), thus classifying them as serine-type peptidases. Additionally, proteolytic cleavage of soluble azoalbumin was blocked by PMSF (65-95% inhibition depending on the fungal isolate). These unprecedented results have demonstrated the capability of the C. haemulonii complex to produce serine-type peptidases with an ability to cleave a broad spectrum of proteins, including key host components.
- MeSH
- bakteriální proteiny chemie metabolismus fyziologie MeSH
- Candida enzymologie izolace a purifikace MeSH
- kandidóza mikrobiologie MeSH
- koncentrace vodíkových iontů MeSH
- kultivační média MeSH
- lidé MeSH
- mnohočetná fungální léková rezistence * MeSH
- molekulová hmotnost MeSH
- serinové endopeptidasy chemie metabolismus fyziologie MeSH
- teplota MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
The Leishmania major leucyl-aminopeptidase (LAPLm), a member of the M17 family of proteases, is a potential drug target for treatment of leishmaniasis. To better characterize enzyme properties, recombinant LAPLm (rLAPLm) was expressed in Escherichia coli. A LAPLm gene was designed, codon-optimized for expression in E. coli, synthesized and cloned into the pET-15b vector. Production of rLAPLm in E. coli Lemo21(DE3), induced for 4 h at 37 °C with 400 μM IPTG and 250 μM l-rhamnose, yielded insoluble enzyme with a low proportion of soluble and active protein, only detected by an anti-His antibody-based western-blot. rLAPLm was purified in a single step by immobilized metal ion affinity chromatography. rLAPLm was obtained with a purity of ~10% and a volumetric yield of 2.5 mg per liter, sufficient for further characterization. The aminopeptidase exhibits optimal activity at pH 7.0 and a substrate preference for Leu-p-nitroanilide (appKM = 30 μM, appkcat = 14.7 s-1). Optimal temperature is 50 °C, and the enzyme is insensitive to 4 mM Co2+, Mg2+, Ca2+ and Ba2+. However, rLAPLm was activated by Zn2+, Mn2+ and Cd2+ but is insensitive towards the protease inhibitors PMSF, TLCK, E-64 and pepstatin A, being inhibited by EDTA and bestatin. Bestatin is a potent, non-competitive inhibitor of the enzyme with a Ki value of 994 nM. We suggest that rLAPLm is a suitable target for inhibitor identification.
- MeSH
- aminopeptidasy * biosyntéza chemie genetika izolace a purifikace MeSH
- Escherichia coli * genetika metabolismus MeSH
- kinetika MeSH
- Leishmania major * enzymologie genetika MeSH
- protozoální proteiny * biosyntéza chemie genetika izolace a purifikace MeSH
- rekombinantní proteiny biosyntéza chemie genetika izolace a purifikace MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
