Different types of enzymes such as lipases, several phosphatases, dehydrogenases, oxidases, amylases and others are well suited for the reactions in SC-CO(2). The stability and the activity of enzymes exposed to carbon dioxide under high pressure depend on enzyme species, water content in the solution and on the pressure and temperature of the reaction system. The three-dimensional structure of enzymes may be significantly altered under extreme conditions, causing their denaturation and consequent loss of activity. If the conditions are less adverse, the protein structure may be largely retained. Minor structural changes may induce an alternative active protein state with altered enzyme activity, specificity and stability.

• Klíčová slova
• enzyme, hydrolysis, inactivation, supercritical carbon dioxide, synthesis,
• MeSH
• aktivace enzymů účinky léků   MeSH
• enzymy chemie   metabolismus   MeSH
• hydrolýza MeSH
• oxid uhličitý chemie   metabolismus   farmakologie   MeSH
• stabilita enzymů MeSH
• teplota MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• enzymy MeSH
• oxid uhličitý MeSH

The renin angiotensin system (RAS) regulates fluid balance, blood pressure and maintains vascular tone. The potent vasoconstrictor angiotensin II (Ang II) produced by angiotensin-converting enzyme (ACE) comprises the classical RAS. The non-classical RAS involves the conversion of Ang II via ACE2 into the vasodilator Ang (1-7) to counterbalance the effects of Ang II. Furthermore, ACE2 converts AngA into another vasodilator named alamandine. The over activation of the classical RAS (increased vasoconstriction) and depletion of the non-classical RAS (decreased vasodilation) results in vascular dysfunction. Vascular dysfunction is the leading cause of atherosclerosis and cardiovascular disease (CVD). Additionally, local RAS is expressed in various tissues and regulates cellular functions. RAS dysregulation is involved in other several diseases such as inflammation, renal dysfunction and even cancer growth. An approach in restoring vascular dysfunction and other pathological diseases is to either increase the activity of ACE2 or reduce the effect of the classical RAS by counterbalancing Ang II effects. The antitrypanosomal agent, diminazene aceturate (DIZE), is one approach in activating ACE2. DIZE has been shown to exert beneficial effects in CVD experimental models of hypertension, myocardial infarction, type 1 diabetes and atherosclerosis. Thus, this review focuses on DIZE and its effect in several tissues such as blood vessels, cardiac, renal, immune and cancer cells.

• Klíčová slova
• angiotensin-converting enzyme II, cardiovascular disease, diminazene aceturate, endothelial dysfunction, renin angiotensin system,
• MeSH
• aktivace enzymů MeSH
• aktivátory enzymů škodlivé účinky   terapeutické užití   MeSH
• angiotensin konvertující enzym 2 metabolismus   MeSH
• diminazen škodlivé účinky   analogy a deriváty   terapeutické užití   MeSH
• kardiovaskulární nemoci farmakoterapie   enzymologie   patofyziologie   MeSH
• lidé MeSH
• nádory farmakoterapie   enzymologie   patofyziologie   MeSH
• renin-angiotensin systém účinky léků   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• ACE2 protein, human MeSH Prohlížeč
• aktivátory enzymů MeSH
• angiotensin konvertující enzym 2 MeSH
• diminazen MeSH
• diminazene aceturate MeSH Prohlížeč

Cytochrome P450 (CYP450), and in particular CYP3A4, is the most abundantly expressed CYP450 isozyme implicated in many drug-drug and medicinal plant-drug interactions. Therefore, incorporation of CYP3A4 enzyme screening at an early stage of drug discovery is preferable in order to avoid enzymatic interactions. Here we present for the first time a paper-based CYP3A4 immobilized sol-gel-derived a platform using resorufin benzyl ether as a fluorogenic enzyme substrate used to investigate enzyme activity. The fluorescence intensity of the product can be simply quantified by using a handheld digital microscope and an image analysis software. The limit of quantitation was 0.35 μM with good precision (RSDs < 4.1%). Furthermore, the assay of CYP3A4 activity on the developed paper-based device provided comparable results with those obtained from conventional well-plates (p > 0.05), while offering simplicity and lower cost. Kinetic parameters of the immobilized CYP3A4 in sol-gel coated paper were calculated from the Lineweaver-Burk plot, including Michaelis constant (Km) and maximum velocity (Vmax), which were 2.71 ± 0.35 μM and 0.43 ± 0.05 μM/min, respectively. Moreover, a functional test of these devices was conducted by assessments of known CYP3A4 inhibitors (i.e. ketoconazole, itraconazole) and inducers (i.e. phenytoin, carbamazepine). To further demonstrate the broad range of uses, the devices were utilized to assay plant extracts i.e. Areca catechu seeds, Camellia sinensis leaves, Eclipta prostrata aerial part, providing results in good agreement with previous studies. Furthermore, the sol-gel immobilized enzyme stored at 4 °C can increase storage stability, offering the activity of 86.3 ± 0.4% after 3-weeks storage, equivalent to the activity of the free enzyme solution after 1-week storage. The developed paper-based devices offer versatility, portability and low-cost.

• Klíčová slova
• Cytochrome P450 enzyme, Fluorescence microscope, Paper-based devices, Sol-gel,
• MeSH
• aktivace enzymů MeSH
• benzenové deriváty chemie   MeSH
• enzymy imobilizované analýza   metabolismus   MeSH
• ethery chemie   MeSH
• gely chemie   MeSH
• lidé MeSH
• molekulární struktura MeSH
• oxaziny chemie   MeSH
• papír * MeSH
• systém (enzymů) cytochromů P-450 analýza   metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• benzenové deriváty MeSH
• enzymy imobilizované MeSH
• ethery MeSH
• gely MeSH
• oxaziny MeSH
• resorufin MeSH Prohlížeč
• systém (enzymů) cytochromů P-450 MeSH

The application of enzymes is a crucial issue for current biotechnological application in pharmaceutical, as well as food and cosmetic industry. Effective platforms for enzyme immobilization are necessary for their industrial use in various biosynthesis procedures. Such platforms must provide high yield of immobilization and retain high activity at various conditions for their large-scale applications. Graphene derivatives such as hydrogenated graphene (graphane) and fluorographene can be applied for enzyme immobilization with close to 100 % yield that can result to activities of the composites significantly exceeding activity of free enzymes. The hydrophobic properties of graphene stoichiometric derivatives allowed for excellent non-covalent bonding of enzymes and their use in various organic solvents. The immobilized enzymes retain their high activities even at elevated temperatures. These findings show excellent application potential of enzyme biocatalysts immobilized on graphene stoichiometric derivatives.

• Klíčová slova
• biocatalysis, enzyme, graphene,
• MeSH
• aktivace enzymů MeSH
• biokatalýza MeSH
• enzymy imobilizované chemie   MeSH
• fluorescenční barviva chemie   MeSH
• grafit chemie   MeSH
• hydrofobní a hydrofilní interakce MeSH
• koncentrace vodíkových iontů MeSH
• lipasa chemická syntéza   MeSH
• nanostruktury chemie   MeSH
• oxidace-redukce MeSH
• povrchové vlastnosti MeSH
• rozpouštědla chemie   MeSH
• stabilita enzymů MeSH
• vysoká teplota MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• enzymy imobilizované MeSH
• fluorescenční barviva MeSH
• grafit MeSH
• lipasa MeSH
• rozpouštědla MeSH

Benzo[a]pyrene (BaP) is a human carcinogen requiring metabolic activation prior to reaction with DNA. Cytochrome P450 (CYP) 1A1 is the most important hepatic and intestinal enzyme in both BaP activation and detoxification. CYP1A2 is also capable of oxidizing BaP, but to a lesser extent. The induction of CYP1A1/2 by BaP and/or β-naphthoflavone in liver and small intestine of rats was investigated. Both BaP and β-naphthoflavone induced CYP1A expression and increased enzyme activities in both organs. Moreover, the induction of CYP1A enzyme activities resulted in an increase in formation of BaP-DNA adducts detected by (32)P-postlabeling in rat liver and in the distal part of small intestine in vivo. The increases in CYP1A enzyme activity were also associated with bioactivation of BaP and elevated BaP-DNA adduct levels in ex vivo incubations of microsomes of both organs with DNA and BaP. These findings indicate a stimulating effect of both compounds on BaP-induced carcinogenesis.

• Klíčová slova
• (32)P-postlabeling, 10-(deoxyguanosin-N(2)-yl)-7,8,9-trihydroxy-7,8,9,10-tetrahydrobenzo[a]pyrene, 5-bromo-4-chloro-3′-indolyphosphate p-toluidine salt, 7-ethoxyresorufin O-deethylation, 7-methoxyresorufin O-deethylation, AHR, BCIP, BNF, BPDE, BaP, BaP-7,8-dihydrodiol-9,10-epoxide, Benzo[a]pyrene, CYP, Cytochrome P450 1A1/2, DMSO, DNA adducts, EROD, Induction, MROD, Metabolic Activation and Detoxification, NBT, PAH, RAL, SDS, TLC, aryl hydrocarbon receptor, benzo[a]pyrene, cytochrome P450, dG-N(2)-BPDE, dimethyl sulfoxide, mEH, microsomal epoxide hydrolase, nitro-blue tetrazolium chloride, polycyclic aromatic hydrocarbon, relative adduct labeling, sodium dodecyl sulfate, thin-layer chromatography, β-naphthoflavone,
• MeSH
• adukty DNA metabolismus   MeSH
• aktivace enzymů účinky léků   MeSH
• benzopyren toxicita   MeSH
• beta-naftoflavon farmakologie   MeSH
• chromatografie na tenké vrstvě MeSH
• cytochrom P-450 CYP1A1 metabolismus   MeSH
• cytochrom P-450 CYP1A2 biosyntéza   genetika   MeSH
• izoenzymy účinky léků   metabolismus   MeSH
• jaterní mikrozomy účinky léků   enzymologie   metabolismus   MeSH
• játra účinky léků   enzymologie   metabolismus   MeSH
• krysa rodu Rattus MeSH
• látky znečišťující životní prostředí toxicita   MeSH
• potkani Wistar MeSH
• tenké střevo účinky léků   enzymologie   metabolismus   MeSH
• western blotting MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• adukty DNA MeSH
• benzopyren MeSH
• beta-naftoflavon MeSH
• cytochrom P-450 CYP1A1 MeSH
• cytochrom P-450 CYP1A2 MeSH
• izoenzymy MeSH
• látky znečišťující životní prostředí MeSH

BACKGROUND: Enzyme active sites can be connected to the exterior environment by one or more channels passing through the protein. Despite our current knowledge of enzyme structure and function, surprisingly little is known about how often channels are present or about any structural features such channels may have in common. RESULTS: Here, we analyze the long channels (i.e. >15 Å) leading to the active sites of 4,306 enzyme structures. We find that over 64% of enzymes contain two or more long channels, their typical length being 28 Å. We show that amino acid compositions of the channel significantly differ both to the composition of the active site, surface and interior of the protein. CONCLUSIONS: The majority of enzymes have buried active sites accessible via a network of access channels. This indicates that enzymes tend to have buried active sites, with channels controlling access to, and egress from, them, and that suggests channels may play a key role in helping determine enzyme substrate.

• MeSH
• aminokyseliny chemie   genetika   MeSH
• enzymy chemie   genetika   MeSH
• iontové kanály fyziologie   MeSH
• katalytická doména MeSH
• konformace proteinů MeSH
• lidé MeSH
• molekulární modely MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• aminokyseliny MeSH
• enzymy MeSH
• iontové kanály MeSH

The demand for food and beverage markets has increased as a result of population increase and in view of health awareness. The quality of products from food processing industry has to be improved economically by incorporating greener methodologies that enhances the safety and shelf life via the enzymes application while maintaining the essential nutritional qualities. The utilization of enzymes is rendered more favorable in industrial practices via the modification of their characteristics as attested by studies on enzyme immobilization pertaining to different stages of food and beverage processing; these studies have enhanced the catalytic activity, stability of enzymes and lowered the overall cost. However, the harsh conditions of industrial processes continue to increase the propensity of enzyme destabilization thus shortening their industrial lifespan namely enzyme leaching, recoverability, uncontrollable orientation and the lack of a general procedure. Innovative studies have strived to provide new tools and materials for the development of systems offering new possibilities for industrial applications of enzymes. Herein, an effort has been made to present up-to-date developments on enzyme immobilization and current challenges in the food and beverage industries in terms of enhancing the enzyme stability.

• Klíčová slova
• Immobilized enzymes, enzyme reusability, enzyme stability, food industry, pharmaceuticals,
• MeSH
• enzymy imobilizované * metabolismus   MeSH
• potravinářský průmysl * MeSH
• stabilita enzymů MeSH
• technologie MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• enzymy imobilizované * MeSH

Enzyme-mediated decomposition of soil organic matter (SOM) is controlled, amongst other factors, by organic matter properties and by the microbial decomposer community present. Since microbial community composition and SOM properties are often interrelated and both change with soil depth, the drivers of enzymatic decomposition are hard to dissect. We investigated soils from three regions in the Siberian Arctic, where carbon rich topsoil material has been incorporated into the subsoil (cryoturbation). We took advantage of this subduction to test if SOM properties shape microbial community composition, and to identify controls of both on enzyme activities. We found that microbial community composition (estimated by phospholipid fatty acid analysis), was similar in cryoturbated material and in surrounding subsoil, although carbon and nitrogen contents were similar in cryoturbated material and topsoils. This suggests that the microbial community in cryoturbated material was not well adapted to SOM properties. We also measured three potential enzyme activities (cellobiohydrolase, leucine-amino-peptidase and phenoloxidase) and used structural equation models (SEMs) to identify direct and indirect drivers of the three enzyme activities. The models included microbial community composition, carbon and nitrogen contents, clay content, water content, and pH. Models for regular horizons, excluding cryoturbated material, showed that all enzyme activities were mainly controlled by carbon or nitrogen. Microbial community composition had no effect. In contrast, models for cryoturbated material showed that enzyme activities were also related to microbial community composition. The additional control of microbial community composition could have restrained enzyme activities and furthermore decomposition in general. The functional decoupling of SOM properties and microbial community composition might thus be one of the reasons for low decomposition rates and the persistence of 400 Gt carbon stored in cryoturbated material.

• MeSH
• aktivace enzymů MeSH
• dusík metabolismus   MeSH
• enzymy metabolismus   MeSH
• hydrolýza MeSH
• mikrobiota * MeSH
• půda chemie   MeSH
• půdní mikrobiologie * MeSH
• uhlík metabolismus   MeSH
• zeměpis MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Arktida MeSH
• Sibiř MeSH
• Názvy látek
• dusík MeSH
• enzymy MeSH
• půda MeSH
• uhlík MeSH

Nepenthes regulates enzyme activities by sensing stimuli from the insect prey. Protein is the best inductor mimicking the presence of an insect prey. Carnivorous plants of the genus Nepenthes have evolved passive pitcher traps for prey capture. In this study, we investigated the ability of chemical signals from a prey (chitin, protein, and ammonium) to induce transcription and synthesis of digestive enzymes in Nepenthes × Mixta. We used real-time PCR and specific antibodies generated against the aspartic proteases nepenthesins, and type III and type IV chitinases to investigate the induction of digestive enzyme synthesis in response to different chemical stimuli from the prey. Transcription of nepenthesins was strongly induced by ammonium, protein and live prey; chitin induced transcription only very slightly. This is in accordance with the amount of released enzyme and proteolytic activity in the digestive fluid. Although transcription of type III chitinase was induced by all investigated stimuli, a significant accumulation of the enzyme in the digestive fluid was found mainly after protein and live prey addition. Protein and live prey were also the best inducers for accumulation of type IV chitinase in the digestive fluid. Although ammonium strongly induced transcription of all investigated genes probably through membrane depolarization, strong acidification of the digestive fluid affected stability and abundance of both chitinases in the digestive fluid. The study showed that the proteins are universal inductors of enzyme activities in carnivorous pitcher plants best mimicking the presence of insect prey. This is not surprising, because proteins are a much valuable source of nitrogen, superior to chitin. Extensive vesicular activity was observed in prey-activated glands.

• Klíčová slova
• Carnivorous plant, Chitin, Chitinase, Enzyme, Nepenthesin, Pitcher plant, Protease,
• MeSH
• Caryophyllales enzymologie   fyziologie   ultrastruktura   MeSH
• chitin metabolismus   MeSH
• chlorid amonný farmakologie   MeSH
• enzymy genetika   metabolismus   MeSH
• koncentrace vodíkových iontů MeSH
• masožravci MeSH
• membránové potenciály MeSH
• regulace genové exprese u rostlin * MeSH
• rostlinné proteiny genetika   metabolismus   MeSH
• sérový albumin hovězí metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• chitin MeSH
• chlorid amonný MeSH
• enzymy MeSH
• rostlinné proteiny MeSH
• sérový albumin hovězí MeSH

Capillary electrophoresis is a modern separation technique characterized by many benefits, which qualify it also for enzyme assays and the study of enzyme kinetics during drug development. Homogeneous or heterogeneous approaches can be followed for the enzymatic incubation. In this study, an immobilization procedure of aldehyde oxidase on magnetic particles was developed considering their integration with capillary electrophoresis. A number of magnetic nano/microparticle types were tested for this purpose, showing that aldehyde oxidase was most active when immobilized on bare silica magnetic nanoparticles. Primarily, the reusability of the enzyme immobilized on bare silica nanoparticles was tested. Three consecutive incubations with substrate could be performed, but the activity considerably dropped after the first incubation. One reason could be an enzyme detachment from the nanoparticles, but no release was detected neither at 4°C nor at 37°C during 5 h. The drop in enzymatic activity observed in consecutive incubations, could also be due to inactivation of the enzyme over time at given temperature. For the immobilized enzyme stored at 4°C, the activity decreased to 83% after 5 h, in contrast with a steep decrease at 37°C to 37%.

• Klíčová slova
• aldehyde oxidase, capillary electrophoresis, enzyme immobilization, magnetic nanoparticles, micellar electrokinetic chromatography,
• MeSH
• aldehydoxidasa analýza   metabolismus   MeSH
• elektroforéza kapilární MeSH
• enzymatické testy * MeSH
• enzymy imobilizované analýza   metabolismus   MeSH
• teplota MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• aldehydoxidasa MeSH
• enzymy imobilizované MeSH