It was originally shown [10] that urease retains its enzymatic activity when adsorbed at bare mercury and solid amalgam surfaces. However the opinion later prevailed that, when adsorbed at bare metal electrodes, proteins are irreversibly denatured. Here we confirm that urease is enzymatically active at a bare solid amalgam surface as found by Santhanam et al., and we show that this enzyme is equally active at a thiol-modified amalgam surface. We also show that it is the reduced form of urease, which is enzymatically active at Hg surfaces. Oxidation of the protein, resulting in formation of disulfide bonds, strongly decreases the enzyme activity. Using constant current chronopotentiometric stripping (CPS) we show that the exposure of surface-attached urease to negative potentials results in the protein unfolding. The extent of the unfolding depends upon the amount of time for which the protein is exposed to negative potentials, and at very short times this unfolding can be avoided. At thiol-modified Hg surfaces the protein is less vulnerable to the effects of the electric field. We conclude that the loss of enzymatic activity, resulting from a 10 min exposure of the protein to -0.58 V, is not due to reduction of the disulfide bonds as suggested by Santhanam et al. This loss is probably a result of protein reorientation, due to reduction of the Hg-S bonds (formed by accessible cysteines), followed by prolonged electric field effect on the surface-attached protein.

• Klíčová slova
• Constant-current chronopotentiometric stripping, Mercury containing electrodes, Protein denaturation at negatively charged surfaces, Protein structure at surfaces, Thiol-modified electrodes, Urease enzymatic activity,
• MeSH
• adsorpce MeSH
• cystein chemie   MeSH
• denaturace proteinů MeSH
• disulfidy chemie   MeSH
• dithiothreitol chemie   MeSH
• elektrochemické techniky MeSH
• elektrody MeSH
• katalýza MeSH
• oxidace-redukce MeSH
• povrchové vlastnosti MeSH
• rtuť chemie   MeSH
• sbalování proteinů MeSH
• sulfhydrylové sloučeniny chemie   MeSH
• teplota MeSH
• ureasa chemie   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• cystein MeSH
• disulfidy MeSH
• dithiothreitol MeSH
• rtuť MeSH
• sulfhydrylové sloučeniny MeSH
• ureasa MeSH

For decades, Hibiscus sabdariffa L. and its phytochemicals have been shown to possess a wide range of pharmacologic properties. In this study, aqueous extract of Hibiscus sabdariffa (AEHS) and its bioactive constituent protocatechuic acid (PCA), have been evaluated in vitro for their antiviral activity against HSV-2 clinical isolates and anti-enzymatic activity against urease. Antiherpetic activity was evaluated by the titer reduction assay in infected Vero cells, and cytotoxicity was evaluated by the neutral red dye-uptake method. Anti-urease activity was determined by a developed Electrospray Ionization-Mass Spectrometry (ESI-MS)-based assay. PCA showed potent anti-HSV-2 activity compared with that of acyclovir, with EC50 values of 0.92 and 1.43 µg∙mL-1, respectively, and selectivity indices > 217 and > 140, respectively. For the first time, AEHS was shown to exert anti-urease inhibition activity, with an IC50 value of 82.4 µg∙mL-1. This, combined with its safety, could facilitate its use in practical applications as a natural urease inhibitor. Our results present Hibiscus sabdariffa L. and its bioactive compound PCA as potential therapeutic agents in the treatment of HSV-2 infection and the treatment of diseases caused by urease-producing bacteria.

• Klíčová slova
• ESI-mass spectrometry-based assay, Hibiscus sabdariffa L., anti-HSV-2 activity, bacterial infection, protocatechuic acid, urease inhibitors,
• MeSH
• acyklovir farmakologie   MeSH
• antivirové látky chemie   izolace a purifikace   farmakologie   MeSH
• Cercopithecus aethiops MeSH
• Hibiscus chemie   MeSH
• hmotnostní spektrometrie s elektrosprejovou ionizací MeSH
• inhibiční koncentrace 50 MeSH
• inhibitory enzymů chemie   izolace a purifikace   farmakologie   MeSH
• kinetika MeSH
• lidský herpesvirus 2 účinky léků   MeSH
• polyfenoly chemie   izolace a purifikace   farmakologie   MeSH
• preklinické hodnocení léčiv MeSH
• rostlinné extrakty chemie   izolace a purifikace   farmakologie   MeSH
• ureasa antagonisté a inhibitory   chemie   MeSH
• Vero buňky MeSH
• vysokoúčinná kapalinová chromatografie MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• acyklovir MeSH
• antivirové látky MeSH
• inhibitory enzymů MeSH
• polyfenoly MeSH
• rostlinné extrakty MeSH
• ureasa MeSH

In the current study, pyroglutamic acid (pGlu), a natural amino acid derivative, has efficiently inhibited the catalytic activities of three important enzymes, namely: Human recombinant phosphodiesterase-5A1 (PDE5A1), human angiotensin-converting enzyme (ACE), and urease. These enzymes were reported to be associated with several important clinical conditions in humans. Radioactivity-based assay, spectrophotometric-based assay, and an Electrospray Ionization-Mass Spectrometry-based method were employed to ascertain the inhibitory actions of pGlu against PDE5A1, ACE, and urease, respectively. The results unveiled that pGlu potently suppressed the activity of PDE5A1 (half-maximal inhibitory concentration; IC50 = 5.23 µM) compared with that of standard drug sildenafil citrate (IC50 = 7.14 µM). Moreover, pGlu at a concentration of 20 µg/mL was found to efficiently inhibit human ACE with 98.2% inhibition compared with that of standard captopril (99.6%; 20 µg/mL). The urease-catalyzed reaction was also remarkably inactivated by pGlu and standard acetohydroxamic acid with IC50 values of 1.8 and 3.9 µM, respectively. Remarkably, the outcome of in vitro cytotoxicity assay did not reveal any significant cytotoxic properties of pGlu against human cervical carcinoma cells and normal human fetal lung fibroblast cells. In addition to in vitro assays, molecular docking analyses were performed to corroborate the outcomes of in vitro results with predicted structure-activity relationships. In conclusion, pGlu could be presented as a natural and multifunctional agent with promising applications in the treatment of some ailments connected with the above-mentioned anti-enzymatic properties.

• Klíčová slova
• ESI-mass spectrometry, angiotensin-converting enzyme, anti-enzymatic properties, cytotoxicity, phosphodiesterase 5, pyroglutamic acid, urease,
• MeSH
• angiotensin konvertující enzym chemie   genetika   metabolismus   MeSH
• buněčné linie MeSH
• cyklické nukleotidfosfodiesterasy, typ 5 chemie   genetika   metabolismus   MeSH
• hmotnostní spektrometrie s elektrosprejovou ionizací MeSH
• inhibiční koncentrace 50 MeSH
• kaptopril chemie   metabolismus   MeSH
• kyselina pyrrolidonkarboxylová chemie   metabolismus   toxicita   MeSH
• kyseliny hydroxamové antagonisté a inhibitory   metabolismus   MeSH
• lidé MeSH
• rekombinantní proteiny biosyntéza   chemie   izolace a purifikace   MeSH
• sildenafil citrát chemie   metabolismus   MeSH
• simulace molekulového dockingu MeSH
• spektrofotometrie MeSH
• terciární struktura proteinů MeSH
• ureasa antagonisté a inhibitory   metabolismus   MeSH
• vazebná místa MeSH
• viabilita buněk účinky léků   MeSH
• vztahy mezi strukturou a aktivitou MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• ACE protein, human MeSH Prohlížeč
• acetohydroxamic acid MeSH Prohlížeč
• angiotensin konvertující enzym MeSH
• cyklické nukleotidfosfodiesterasy, typ 5 MeSH
• kaptopril MeSH
• kyselina pyrrolidonkarboxylová MeSH
• kyseliny hydroxamové MeSH
• PDE5A protein, human MeSH Prohlížeč
• rekombinantní proteiny MeSH
• sildenafil citrát MeSH
• ureasa MeSH

• MeSH
• aktivace enzymů MeSH
• koncentrace vodíkových iontů * MeSH
• kovy farmakologie   MeSH
• krmivo pro zvířata analýza   MeSH
• rostliny účinky léků   enzymologie   MeSH
• skot MeSH
• ureasa metabolismus   MeSH
• zvířata MeSH
• Check Tag
• skot MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• kovy MeSH
• ureasa MeSH

Urinary-based infections affect millions of people worldwide. Such bacterial infections are mainly caused by Escherichia coli (E. coli) biofilm formation in the bladder and/or urinary catheters. Herein, the authors present a hybrid enzyme/photocatalytic microrobot, based on urease-immobilized TiO2 /CdS nanotube bundles, that can swim in urea as a biocompatible fuel and respond to visible light. Upon illumination for 2 h, these microrobots are able to remove almost 90% of bacterial biofilm, due to the generation of reactive radicals, while bare TiO2 /CdS photocatalysts (non-motile) or urease-coated microrobots in the dark do not show any toxic effect. These results indicate a synergistic effect between the self-propulsion provided by the enzyme and the photocatalytic activity induced under light stimuli. This work provides a photo-biocatalytic approach for the design of efficient light-driven microrobots with promising applications in microbiology and biomedicine.

• Klíčová slova
• TiO 2 nanotubes, bacterial biofilms, enzymatic, micromotors, photocatalysis, urinary infections,
• MeSH
• biofilmy * MeSH
• Escherichia coli * MeSH
• katalýza MeSH
• lidé MeSH
• močovina farmakologie   MeSH
• robotika * MeSH
• titan * farmakologie   MeSH
• ureasa farmakologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• močovina MeSH
• titan * MeSH
• ureasa MeSH