Enzyme Carbonic Anhydrase Research Articles

The carbonic anhydrase enzymes as new targets for the management of neglected tropical diseases.

Diseases caused by protozoan parasites represent a huge challenge to global health care, due to the lack of selective and efficient treatments for the management and spreading of such complex pathologies. The protozoans Trypanosoma cruzi (T. cruzi) and Leishmania spp. are the etiological agents of the so-called neglected tropical diseases (NTDs), that is, Chagas disease (CD) and leishmaniasis, respectively. In such a context, the metalloenzymes carbonic anhydrases (CAs; EC 4.2.1.1) emerged as potential protozoan druggable enzymes, being involved in the parasites' life cycle. Several studies suggested the relevance of the protozoan-expressed CAs as future candidates for the management of NTDs.

Hamamelitannin’s Antioxidant Effect and Its Inhibition Capability on α-Glycosidase, Carbonic Anhydrase, Acetylcholinesterase, and Butyrylcholinesterase Enzymes

Hamamelitannin (2′,5-di-O-galloyl-hamamelose) bears two-gallate moieties in its structure, and is a natural phenolic product in the leaves and the bark of Hamamelis virginiana. The antioxidant capacity of hamamelitannin was evaluated by a range of methods, with the following findings: the ability to reduce potassium ferric cyanide; the scavenging of N,N-dimethyl-p-phenylenediamine dihydrochloride radical (DMPD•+); the scavenging of 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulphonate) radical (ABTS•+); the scavenging of 1,1-diphenyl-2-picrylhydrazyl radical (DPPH•); and the ability to reduce cupric ions (Cu2+). Additionally, reference antioxidants of α-Tocopherol, butylated hydroxyanisole (BHA), Trolox, and butylated hydroxytoluene (BHT) were used for comparison. For DPPH radical scavenging, hamamelitannin had an IC50 value of 19.31 μg/mL, while the IC50 values for BHA, BHT, Trolox, and α-Tocopherol were 10.10, 25.95, 7.05, and 11.31 μg/mL, respectively. The study found that hamamelitannin functioned similarly to BHA, α-tocopherol, and Trolox in terms of DPPH• scavenging, but better than BHT. Additionally, as a polyphenolic secondary metabolite, the hamamelitannin inhibition capability of several metabolic enzymes was demonstrated, including acetylcholinesterase (AChE), butyrylcholinesterase (BChE), carbonic anhydrase I (CA I), carbonic anhydrase II (CA II) and α-glycosidase. The Ki values of hamamelitannin exhibited 7.40, 1.99, 10.18, 18.26, and 25.79 nM toward AChE, BChE, hCA I, hCA II, and α-glycosidase, respectively.

Inhibition of Pseudomonas aeruginosa Carbonic Anhydrases, Exploring Ciprofloxacin Functionalization Toward New Antibacterial Agents: An In-Depth Multidisciplinary Study.

Ciprofloxacin (CPX) is one of the most employed antibiotics in clinics to date. However, the rise of drug-resistant bacteria is dramatically impairing its efficacy, especially against life-threatening pathogens, such as Pseudomonas aeruginosa. This Gram-negative bacterium is an opportunistic pathogen, often infecting immuno-compromised patients with severe or fatal outcomes. The evidence of the possibility of exploiting Carbonic Anhydrase (CA, EC: 4.2.1.1) enzymes as pharmacological targets along with their role in P. aeruginosa virulence inspired the derivatization of CPX with peculiar CA-inhibiting chemotypes. Thus, a large library of CPX derivatives was synthesized and tested on a panel of bacterial CAs and human isoenzymes I and II. Selected derivatives were evaluated for antibacterial activity, revealing bactericidal and antibiofilm properties for some compounds. Importantly, promising preliminary absorption, distribution, metabolism, and excretion (ADME) properties in vitro were found and no cytotoxicity was detected for some representative compounds when tested in Galleria mellonella larvae.

The response mechanism of alkalophilic Nitzschia sp. NW129 to low alkalinity-A study combining physiological and transcriptional analysis

Global aquatic acidification significantly threatens alkaline lake ecosystems. The mechanisms by which alkaliphilic microalgae, the key producers in these ecosystems, respond to reduced environmental alkalinity remain poorly understood. Here, we investigated the responses of alkalophilic Nitzschia sp. NW129 to low alkalinity (pH 9.2) through integrated physiological-biochemical and transcriptomic analyses. Relative to the control (pH 11.5), we observed a 60.1 % decrease in polysaccharide content, while total lipids and proteins increased by 1.74-fold and 2-fold, respectively. Transcriptome analysis revealed up-regulation of genes encoding carbonic anhydrase (CA) and malic enzyme (ME), along with those involved in glycolysis and fatty acid (FA) synthesis, compensating for carbon supply and shifting carbon flux from carbohydrate synthesis to lipid accumulation. Enhanced expression of TCA cycle genes and those encoding F-ATP synthase and inorganic pyrophosphatase (PPase) provided sufficient energy for cellular homeostasis, further facilitated by the up-regulated expression of ATP-dependent V-ATPase and ABC transporter genes. Temporal analysis revealed that the expression of genes involved in protein synthesis pathways was up-regulated on days 1 and 4 but notably down-regulated on day 2, suggesting protein degradation at this time to balance energy supply for adaptation. Despite these coping shifts, impairments in photosynthetic energy dissipation and electron transport, along with transcriptional changes including down-regulating cell cycle and inducing apoptotic pathways, ultimately caused a substantial reduction in biomass. These findings provide a basic understanding of the response mechanisms of alkalophilic microalgae to low alkalinity stress, which should aid to develop strategies to improve microalgal tolerance against acidification.

Multi- and poly-pharmacology of carbonic anhydrase inhibitors.

Eight genetically distinct families of the enzyme carbonic anhydrase (CA, EC 4.2.1.1) were described in organisms allover the phylogenetic tree. They catalyze the hydration of CO2 to bicarbonate and protons, and are involved in pH regulation, chemosensing and metabolism. The 15 α-CA isoforms present in humans are pharmacological drug targets known for decades, their inhibitors being used as diuretics, antiglaucoma, antiepileptic or antiobesity drugs, as well as for the management of acute mountain sickness, idiopathic intracranial hypertension and recently, as antitumor theragnostic agents. Other potential applications include the use of CA inhibitors (CAIs) in inflammatory conditions, cerebral ischemia, neuropathic pain, or for Alzheimer's/Parkinson's disease management. CAs from pathogenic bacteria, fungi, protozoans and nematodes started to be considered as drug targets in recent years, with notable advances registered ultimately. CAIs have a complex multipharmacology probably unique to this enzyme, which has been exploited intensely but may lead to other relevant applications in the future, due to the emergence of drug design approaches which afforded highly isoform-selective compounds for most α-CAs known to date. They belong to a multitude of chemical classes (sulfonamides and isosteres, (iso)coumarins and related compounds, mono- and dithiocarbamates, selenols, ninhydrines, boronic acids, benzoxaboroles, etc). The polypharmacology of CAIs will also be discussed since drugs originally discovered for the treatment of non-CA related conditions (topiramate, zonisamide, celecoxib, pazopanib, thiazide and high-ceiling diuretics) show efective inhibition against many CAs, which led to their repurposing for diverse pharmacological applications. Significance Statement Carbonic anhydrase inhibitors have multiple pharmacologic applications as diuretics, antiglaucoma, antiepileptic, antiobesity, anti-acute mountain sickness, anti-idiopathic intracranial hypertension and as antitumor drugs. Their use in inflammatory conditions, cerebral ischemia, neuropathic pain, or neurodegenerations started to be investigated recently. Parasite carbonic anhydrases are also drug targets for antiinfectives with novel mechanisms of action which can by pass drug resistance to commonly used such agents. Drugs discovered for the management of other conditions that effectively inhibit these enzymes exert interesting polypharmacologic effects.

Comparative study of stability and activity of wild-type and mutant human carbonic anhydrase II enzymes using molecular dynamics and docking simulations

The human carbonic anhydrase II (HCA II) enzyme is a cytosolic protein that catalyzes the reversible hydration of carbon dioxide (CO2). Considering the critical role of the HCA II and the effects of some mutations on the activity and stability of the enzyme in humans, several computational methods are used to study the structure and dynamics of the wild-type and the mutant enzymes with three ligands, CO2, 4-nitrophenyl acetate and acetazolamide. Our results of MD simulation of a wild-type enzyme with 4-nitrophenyl acetate show that it created essential effects on the fluctuation of this enzyme and made it more unstable and less compact than the same enzyme without ligand. In the MD of the mutant enzyme with 4-nitrophenyl acetate ligand, no significant difference is observed between with and without ligand. The affinity of the wild-type enzyme to the 4-nitrophenyl acetate is notably higher than the mutant enzyme with the same ligand. Furthermore, results showed that wild-type and mutant enzymes with CO2 are more favorable in stability and flexibility than the same enzymes without ligand. The MD results of wild-type with acetazolamide indicate instability compare without ligand, but in MD of mutant enzyme with acetazolamide show that it more stable and compact than the same enzyme without ligand. Finally, Comparing protein trajectories to assess the impact of ligands on the stability and activity of HCA II enzymes can have medical applications and can in the engineering and design of new variants of carbonic anhydrase enzyme.

Photosynthesizing carbonate/nitrate into Chlorococcum humicola biomass for biodiesel and Bacillus coagulans-based biohydrogen production

Biofuel can be generated by different organisms using various substrates. The green alga Chlorococcum humicola OQ934050 exhibited the capability to photosynthesize carbonate carbon, maybe via the activity of carbonic anhydrase enzymes. The optimum treatment is C:N ratio of 1:1 (0.2 mmoles sodium carbonate and 0.2 mmoles sodium nitrate) as it induced the highest dry mass (more than 0.5 mg.mL−1). At this combination, biomass were about 0.2 mg/mL−1 carbohydrates, 0.085 mg/mL−1 proteins, and 0.16 mg/mL−1 oil of this dry weight. The C/N ratios of 1:1 or 10:1 induced up to 30% of the Chlorococcum humicola dry mass as oils. Growth and dry matter content were hindered at 50:1 C/N and oil content was reduced as a result. The fatty acid profile was strongly altered by the applied C.N ratios. The defatted leftovers of the grown alga, after oil extraction, were fermented by a newly isolated heterotrophic bacterium, identified as Bacillus coagulans OQ053202, to evolve hydrogen content as gas. The highest cumulative hydrogen production and reducing sugar (70 ml H2/g biomass and 0.128 mg/ml; respectively) were found at the C/N ratio of 10:1 with the highest hydrogen evolution efficiency (HEE) of 22.8 ml H2/ mg reducing sugar. The optimum treatment applied to the Chlorococcum humicola is C:N ratio of 1:1 for the highest dry mass, up to 30% dry mass as oils. Some fatty acids were induced while others disappeared, depending on the C/N ratios. The highest cumulative hydrogen production and reducing sugar were found at the C/N ratio of 10:1.

Interaction of Micro- and Nanoplastics with Enzymes: The Case of Carbonic Anhydrase.

Microplastics (MPs) and nanoplastics (NPs) have emerged as significant environmental pollutants with potential detrimental effects on ecosystems and human health. Several studies indicate their interaction with enzymes; this topic represents a multifaceted research field encompassing several areas of interest from the toxicological and ecotoxicological impact of MPs and NPs on humans and wildlife to the biodegradation of plastics by microbial enzymes. This review aims to provide a critical analysis of the state-of-the-art knowledge of the interaction of MPs and NPs on the enzyme carbonic anhydrase (CA), providing recent insights, analyzing the knowledge gaps in the field, and drawing future perspectives of the research and its application. CA is a widespread and crucial enzyme in various organisms; it is critical for various physiological processes in animals, plants, and bacteria. It catalyzes the reversible hydration of CO2, which is essential for respiration, acid-base balance, pH homeostasis, ion transport, calcification, and photosynthesis. Studies demonstrate that MPs and NPs can inhibit CA activity with mechanisms including adsorption to the enzyme surface and subsequent conformational changes. In vitro and in silico studies highlight the role of electrostatic and hydrophobic interactions in these processes. In vivo studies present mixed results, which are influenced by factors like particle type, size, concentration, and organism type. Moreover, the potentiality of the esterase activity of CA for plastic degradation is discussed. The complexity of the interaction between CA and MPs/NPs underscores the need for further research to fully understand the ecological and health impacts of MPs and NPs on CA activity and expression and glimpses of the potentiality and perspectives in this field.

Molecular docking, microwave-assisted synthesis, characterization, and preliminary evaluation of the anti-microbial activity of new sulfonamide derivatives of the 1, 2, 4-triazole-3-thiol ring system

A new sulfonamide derivative containing a 1,2,4-Triazole-3-thiol ring was synthesized and characterized using FT-IR and 1H-NMR. The microwave-assisted chemical synthesis of the 1,2,4-Triazole-3-thiol ring system resulted in good yield and purity. The synthetic compounds were then subjected to in vitro evaluation for antimicrobial study. All synthetic compounds show high activity against Gram-positive bacteria (S. aureus, S. pneumonia, and B. subtilis) and high activity against Gram-negative bacteria (P. aeruginosa, and H. pylori), with less activity against (N. gonorrhoeae, and E. coli). Also, it shows high activity against fungi (C. albicans). In this study, we utilized computational methods to design new derivatives that target the carbonic anhydrase enzyme of H. pylori (PDB: 4YGF). All the target compounds interact with the enzyme’s active site, resulting in a disturbance of the acid-base balance affecting the virulence and pathogenicity.

Intensified CO2 Capture in Structured Microreactors with Carbonic Anhydrase Enzyme Immobilized on Open-Cell Foam Packings

Intensified CO₂ Capture in Structured Microreactors with Carbonic Anhydrase Enzyme Immobilized on Open-Cell Foam Packings

In Silico Study, Synthesis and Evaluation of Cytotoxic Activity of New Sulfonamide-Isatin Derivatives as Carbonic Anhydrase Enzyme Inhibitors

Aim: Design, molecular docking, synthesis, and evaluation of cytotoxic activity of new compounds I, II, III, and IV that have isatin-sulfonamide derivatives. Materials and Methods: for chemical synthesis, chemical compounds such as sulfonamide, 4-amino ethyl benzoate, isatin, and its derivatives were used. For the docking study (MOE), software program version 2015.10 was used. The MTT assay was utilized to predict the cytotoxic activity. Results: The synthesized compounds demonstrated significant inhibition of carbonic anhydrase XII activity through molecular docking, as well as significant inhibition of cancer cell viability. Compounds II and IV show higher S-scores than acetazolamide. Also, the MTT assay shows that compounds II and IV have IC50 values of 0.06 µM and 0.105 µM against MCF-7 cells, respectively, while acetazolamide has an IC50 value of 0.394 µM. While acetazolamide had an IC50 of 0.901 µM, compounds II and IV had IC50s of 0.063 µM and 0.114 µM against Hct116 cells, respectively. The MTT assay explains compounds II and IV have better cytotoxic activity compared with acetazolamide. Conclusion: New compounds that were produced showed signs of cytotoxicity and carbonic anhydrase inhibitory qualities.

Fungal carbonatogenesis process mediates zinc and chromium removal via statistically optimized carbonic anhydrase enzyme

IntroductionWith rapid elevation in population, urbanization and industrialization, the environment is exposed to uncontrolled discharge of effluents filled with broad-spectrum toxicity, persistence and long-distance transmission anthropogenic compounds, among them heavy metals. That put our ecosystem on the verge or at a stake of drastic ecological deterioration, which eventually adversely influence on public health. Therefore, this study employed marine fungal strain Rhodotorula sp. MZ312369 for Zn2+ and Cr6+ remediation using the promising calcium carbonate (CaCO3) bioprecipitation technique, for the first time.ResultsInitially, Plackett–Burman design followed by central composite design were applied to optimize carbonic anhydrase enzyme (CA), which succeeded in enhancing its activity to 154 U/mL with 1.8-fold increase comparing to the basal conditions. The potentiality of our biofactory in remediating Zn2+ (50 ppm) and Cr6+ (400 ppm) was monitored through dynamic study of several parameters including microbial count, CA activity, CaCO3 weight, pH fluctuation, changing the soluble concentrations of Ca2+ along with Zn2+ and Cr6+. The results revealed that 9.23 × 107 ± 2.1 × 106 CFU/mL and 10.88 × 107 ± 2.5 × 106 CFU/mL of cells exhibited their maximum CA activity by 124.84 ± 1.24 and 140 ± 2.5 U/mL at 132 h for Zn2+ and Cr6+, respectively. Simultaneously, with pH increase to 9.5 ± 0.2, a complete removal for both metals was observed at 168 h; Ca2+ removal percentages recorded 78.99% and 85.06% for Zn2+ and Cr6+ remediating experiments, respectively. Further, the identity, elemental composition, functional structure and morphology of bioremediated precipitates were also examined via mineralogical analysis. EDX pattern showed the typical signals of C, O and Ca accompanying with Zn2+ and Cr6+ peaks. SEM micrographs depicted spindle, spherical and cubic shape bioliths with size range of 1.3 ± 0.5–23.7 ± 3.1 µm. Meanwhile, XRD difractigrams unveiled the prevalence of vaterite phase in remediated samples. Besides, FTIR profiles emphasized the presence of vaterite spectral peaks along with metals wavenumbers.ConclusionCA enzyme mediated Zn2+ and Cr6+ immobilization and encapsulation inside potent vaterite trap through microbial biomineralization process, which deemed as surrogate ecofriendly solution to mitigate heavy metals toxicity and restrict their mobility in soil and wastewater.

Investigating Active Site Binding of Ligands to High and Low Activity Carbonic Anhydrase Enzymes Using Native Mass Spectrometry.

Carbonic anhydrases (CAs) are a family of enzymes that play an important pH regulatory role in health and disease. While different CA isozymes have a high degree of structural similarity, they have variable enzymatic activity, with CA III being the least active and having less than 1% of the activity of CA II, the most active. Furthermore, ligand binding studies for CA III are limited, and a resulting lack of chemical probes impedes understanding of this CA isozyme in comparison to other CA family members where studies are abundant. Therefore, we employed native mass spectrometry (nMS), also known as intact mass spectrometry, to assess ligand binding to CA II and CA III and discovered two novel compounds that for the first time display strong binding to CA III. We present a new data visualization and quantification tool developed to display native mass spectra as an intuitive stacked heat map representation for rapidly interpreting the results of ligand-protein binding from nMS screening.

Acetazolamide suppresses the progression of hepatocellular carcinoma induced by diethylnitrosamine in Wistar albino rats.

Hepatocellular carcinoma (HCC) continues to be the most prevalent type of liver cancer worldwide. Diethylnitrosamine (DEN)-induced HCC is an extensively used hepatic cancer model in experimental animals. Acetazolamide (AZA) is a carbonic anhydrase enzyme inhibitor. This study aimed to assess the therapeutic mechanism of AZA against DEN-induced HCC. Thirty male Wistar albino rats were divided equally into three groups. Group I (C): control group, Group II (HCC): DEN-induced HCC, and Group III (HCC/AZA): AZA-treated HCC. Verification of the HCC induced by DEN was confirmed by elevated liver enzymes' activities, and increased α-fetoprotein (AFP) levels, as well as distinct liver architecture changes. On the other hand, the AZA-treated HCC group experienced decreases in the activities of serum liver enzymes and AFP levels, as well as, regulated liver architecture. Additionally, it downregulated p-p38 MAPK/p-JNK1/JNK2/p-C-Jun/p-NF-κB p65 protein expressions. Moreover, it ameliorated autophagy by controlling the expression of the p-AMPK/p-mTOR1/LC3 I/II proteins. Furthermore, it downregulated the relative gene expressions of carbonic anhydrase-IX (CAIX) and hexokinase-II (HKII). Histopathological examination of AZA-treated HCC liver tissues supported these findings. Conclusion: AZA provides a new dimension in ameliorating experimentally induced HCC through regulation of hepatic biomarkers, antioxidant status, inflammatory markers, and autophagy, mediated by amelioration of CAIX and HKII gene expressions.

Pharmacological mechanisms involved in the diuretic activity of the ethanol-soluble fraction of Baccharis milleflora (Less.) DC. - An ethnopharmacological investigation

Ethnopharmacological relevanceBaccharis milleflora (Less.) DC. is a plant native to Brazil that is frequently used in traditional medicine as a diuretic and antihypertensive. However, even though it is traditionally used for these purposes, its diuretic and hypotensive effects have not been fully elucidated. AimInvestigate the cardiorenal effects of the ethanol-soluble fraction (ESBM) of Baccharis milleflora in normotensive rats. Materials and methodsCladodes of B. milleflora were analyzed using light and scanning electron microscopy to provide anatomical data to support quality control. Subsequently, the ESBM was obtained and analyzed using LC-DAD-MS, and its components were annotated. The acute toxicity of ESBM was assessed in female Wistar rats. The acute and prolonged diuretic and hypotensive effects were then studied in Wistar rats. Finally, we assessed the mechanisms responsible for the diuretic effects of ESBM, including the activity of renal Na+/K+/ATPase, angiotensin-converting enzyme, and erythrocyte carbonic anhydrase. Additionally, we also investigated the involvement of bradykinin, prostaglandins, and nitric oxide. ResultsFrom LC-DAD-MS data, thirty-three metabolites were identified from ESBM, including chlorogenic acids, glycosylated phenolic derivatives, C-glycosylated flavones, and O-glycosylated flavonols. No signs of acute toxicity were observed in female rats. The findings showed that ESBM had significant diuretic and natriuretic effects, as well as a potassium-sparing effect. The treatment with ESBM was able to significantly decrease serum levels of creatinine and malondialdehyde, and also significantly increase levels of nitrite, an indirect marker of nitric oxide bioavailability. Furthermore, pre-treatment with L-NAME abolished all diuretic effects induced by ESBM. ConclusionThis study presented important morpho-anatomical and phytochemical data that support the quality control of Baccharis milleflora. The ESBM exhibited a significant diuretic and natriuretic effect following acute and seven-days repeated treatment in Wistar rats, without affecting renal potassium elimination. These effects appear to be dependent on the activation of the nitric oxide-cyclic GMP pathway. This study suggests the potential use of B. milleflora preparations in clinical situations where a diuretic effect is needed.

Biosilica-coated carbonic anhydrase displayed on Escherichia coli: A novel design approach for efficient and stable biocatalyst for CO2 sequestration

A robust and stable carbonic anhydrase (CA) system is indispensable for effectively sequestering carbon dioxide to mitigate climate change. While microbial surface display technology has been employed to construct an economically promising cell-displayed CO2-capturing biocatalyst, the displayed CA enzymes were prone to inactivation due to their low stability in harsh conditions. Herein, drawing inspiration from biomineralized diatom frustules, we artificially introduced biosilica shell materials to the CA macromolecules displayed on Escherichia coli surfaces. Specifically, we displayed a fusion of CA and the diatom-derived silica-forming Sil3K peptide (CA-Sil3K) on the E. coli surface using the membrane anchor protein Lpp-OmpA linker. The displayed CA-Sil3K (dCA-Sil3K) fusion protein underwent a biosilicification reaction under mild conditions, resulting in nanoscale self-encapsulation of the displayed enzyme in biosilica. The biosilicified dCA-Sil3K (BS-dCA-Sil3K) exhibited improved thermal, pH, and protease stability and retained 63 % of its initial activity after ten reuses. Additionally, the BS-dCA-Sil3K biocatalyst significantly accelerated the CaCO3 precipitation rate, reducing the time required for the onset of CaCO3 formation by 92 % compared to an uncatalyzed reaction. Sedimentation of BS-dCA-Sil3K on a membrane filter demonstrated a reliable CO2 hydration application with superior long-term stability under desiccation conditions. This study may open new avenues for the nanoscale-encapsulation of enzymes with biosilica, offering effective strategies to provide efficient, stable, and economic cell-displayed biocatalysts for practical applications.

Conserved and repetitive motifs in an intrinsically disordered protein drive ⍺-carboxysome assembly

All cyanobacteria and some chemoautotrophic bacteria fix CO2 into sugars using specialized proteinaceous compartments called carboxysomes. Carboxysomes enclose the enzymes Rubisco and carbonic anhydrase inside a layer of shell proteins to increase the CO2 concentration for efficient carbon fixation by Rubisco. In the ⍺-carboxysome lineage, a disordered and highly repetitive protein named CsoS2 is essential for carboxysome formation and function. Without it, the bacteria require high CO2 to grow. How does a protein predicted to be lacking structure serve as the architectural scaffold for such a vital cellular compartment? In this study, we identify key residues present in the repeats of CsoS2, VTG and Y, which are necessary for building functional ⍺-carboxysomes in vivo. These highly conserved and repetitive residues contribute to the multivalent binding interaction and phase separation behavior between CsoS2 and shell proteins. We also demonstrate 3-component reconstitution of CsoS2, Rubisco, and shell proteins into spherical condensates, and show the utility of reconstitution as a biochemical tool to study carboxysome biogenesis. The precise self-assembly of thousands of proteins is crucial for carboxysome formation, and understanding this process could enable their use in alternative biological hosts or industrial processes as effective tools to fix carbon.

A study of bacteria producing carbonic anhydrase enzyme for CaCO3 precipitation and soil biocementation

We study the carbonic anhydrase (CA) pathway using autochthonous CA-producing bacteria as a means of inducing calcite precipitation, which acts as a biocement to improve the engineering soil properties. Forty different microbial strains producing CA were isolated from the foundation soil of a railway embankment in Prickwillow, UK. Three of the best CA-producing strains were selected and identified by DNA sequencing as Bacillus licheniformis, Bacillus toyonensis and Bacillus pumilus with CA activity values respectively of 1.79 U/ml, 1.42 U/ml and 1.55 U/ml. To optimise the treatments, we investigated the effect of pH, temperature, zinc co-factor and cementation solution molarity on the growth and CA activity and bioprecipitates, with CO2 added in the form of bicarbonate. Scanning electron microscope (SEM) analysis of the bioprecipitates showed that these had characteristic morphologies of calcite and vaterite crystals. The formation of calcite was further corroborated by FT-IR and Raman analysis of bioprecipitates. The precultured bacteria were injected into the fine-grained soil together with cementation solution. Unconfined compressive strength in treated soil increased up to 1 MPa, and its calcium carbonate content increased by 2.78%. This, as well as the stability of the treated soil upon water immersion, proved the biocementation of the fine-grained soil. These findings suggest the potential of employing the CA biocementation route for soil stabilisation pending further development of the technique.

Immobilization of carbonic anhydrase on bentonite – chitosan composite and determination of its kinetic parameters and CO2 removal capacity

Greenhouse gas accumulation in the atmosphere resulting from industrialization and human activities is accepted as the main cause of climate change. Increasing temperatures by greenhouse gases have severe effects on meteorological and climatic events along with reduced available water resources. Carbon dioxide (CO2) is known as the most serious anthropogenic greenhouse gas in the atmosphere. In recent years the systems prepared by immobilizing carbonic anhydrase enzymes using CO2 as a substrate on some matrices are predominantly preferred. In this study, the bentonite-chitosan composite material was prepared as immobilization surface. The hCA I purified from human erythrocytes was immobilized onto the composite material by glutaraldehyde-mediated cross-linking technique. Immobilized hCA I retained 87.5 % of its initial activity 30 days of incubation at 4°C. Besides, after 12 cycles of use the relative activity was 89.1 %. In addition, the CO2 removal capacity of immobilized hCA I was found as 7.41±0.95 mg CaCO3/mg hCA I with CaCO3 precipitation method. These results show that our novel composite hold a great potential as a CO2 removal tool.

Proximal tubule hypertrophy and hyperfunction: a novel pathophysiological feature in disease states.

The role of proximal tubules (PTs), a major component of the renal tubular structure in the renal cortex, has been examined extensively. Along with its physiological role in the reabsorption of various molecules, including electrolytes, amino acids and monosaccharides, transcellular transport of different hormones and regulation of homeostasis, pathological events affecting PTs may underlie multiple disease states. PT hypertrophy or a hyperfunctioning state, despite being a compensatory mechanism at first in response to various stimuli or alterations at tubular transport proteins, have been shown to be critical pathophysiological events leading to multiple disorders, including diabetes mellitus, obesity, metabolic syndrome and congestive heart failure. Moreover, pharmacotherapeutic agents have primarily targeted PTs, including sodium-glucose cotransporter 2, urate transporters and carbonic anhydrase enzymes. In this narrative review, we focus on the physiological role of PTs in healthy states and the current understanding of the PT pathologies leading to disease states and potential therapeutic targets.