Design of a Superpositively Charged Enzyme: Human Carbonic Anhydrase II Variant with Ferritin Encapsulation and Immobilization.

Supercharged proteins exhibit high solubility and other desirable properties, but no engineered superpositively charged enzymes have previously been made. Superpositively charged variants of proteins such as green fluorescent protein have been efficiently encapsulated within Archaeoglobus fulgidus thermophilic ferritin (AfFtn). Encapsulation by supramolecular ferritin can yield systems with a variety of sequestered cargo. To advance applications in enzymology and green chemistry, we sought a general method for supercharging an enzyme that retains activity and is compatible with AfFtn encapsulation. The zinc metalloenzyme human carbonic anhydrase II (hCAII) is an attractive encapsulation target based on its hydrolytic activity and physiologic conversion of carbon dioxide to bicarbonate. A computationally designed variant of hCAII contains positively charged residues substituted at 19 sites on the protein's surface, resulting in a shift of the putative net charge from -1 to +21. This designed hCAII(+21) exhibits encapsulation within AfFtn without the need for fusion partners or additional reagents. The hCAII(+21) variant retains esterase activity comparable to the wild type and spontaneously templates the assembly of AfFtn 24mers around itself. The AfFtn-hCAII(+21) host-guest complex exhibits both greater activity and thermal stability when compared to hCAII(+21). Upon immobilization on a solid support, AfFtn-hCAII(+21) retains enzymatic activity and exhibits an enhancement of activity at elevated temperatures.

A novel nickel-modified nano-magnetite for isolation of histidine-tagged proteins expressed in Escherichia coli.

Nano-magnetite with superparamagnetism could be coated by some organic compounds or by nano Au or Pt via surface modifications with multi-step reactions for the applications of isolating histidine-tagged (His-tagged) proteins. Introducing active sites of binding histidine onto the surface of nano-magnetite was the ultimate task. However, multi-step treatments might result in departure of the coatings from the surface of the nano-magnetite, which led to loss of active sites. In this work, we reported a convenient and efficient way of treating nano-magnetites and applied them in isolating His-tagged proteins. Carboxylates were introduced on the surface of home-made nano-magnetite directly via ultrasonic mixing with sodium bitartrate rather than complicated surface modifications, which was proved by thermogravimetric analyses. Ni2+ was, therefore, caught by the carboxylates of the coating via the coordinate interaction, demonstrated by X-ray photoelectron spectra. The coated magnetic nanoparticles with the bonded Ni2+ were successfully employed to selectively bind and separate recombinant His-tagged proteins directly from the mixture of Escherichia coli cell lysate, and showed wonderful affinity for His-tagged proteins with the saturated adsorption amount being 556 mg g-1. Additionally, such functionalized nano-magnetite manifested the excellent recyclability in isolating His-tagged proteins.

Molecular cloning and transcriptional regulation of two γ-carbonic anhydrase genes in the green macroalga Ulva prolifera.

Ulva prolifera O.F. Müller (Ulvophyceae, Chlorophyta) is well known as a typical green-tide forming macroalga which has caused the world's largest macroalgal blooms in the Yellow Sea of China. In this study, two full-length γ-carbonic anhydrase (γ-CA) genes (UpγCA1 and UpγCA2) were cloned from U. prolifera. UpγCA1 has three conserved histidine residues, which act as an active site for binding a zinc metal ion. In UpγCA2, two of the three histidine residues were replaced by serine and arginine, respectively. The two γ-CA genes are clustered together with other γ-CAs in Chlorophyta with strong support value (100% bootstrap) in maximum likelihood (ML) phylogenetic tree. Quantitative real-time PCR (qRT-PCR) analysis showed that stressful environmental conditions markedly inhibited transcription levels of these two γ-CA genes. Low pH value (pH 7.5) significantly increased transcription level of UpγCA2 not UpγCA1 at 12 h, whereas high pH value (pH 8.5) significantly inhibited the transcription of these two γ-CA genes at 6 h. These findings enhanced our understanding on transcriptional regulation of γ-CA genes in response to environmental factors in U. prolifera.

Synthesis and biological evaluation of bromophenol derivatives with cyclopropyl moiety: Ring opening of cyclopropane with monoester.

Trans-(1R*,2R*,3R*)-Ethyl 2-(3,4-dimethoxyphenyl)-3-methylcyclopropane-1-carboxylate (6) and its cis isomer 7 were obtained from the reaction of the methyl isoeugenol (5) with ethyl diazoacetate. The reduction and bromination reactions of the ester 6 and 7 together with the hydrolysis of all esters were carried out. Opening ring of cyclopropane was observed in the reaction of 7 with bromine. The opening of cyclopropane ring with COOR and synthesis of esters, alcohols and acids (6-26) are new. These obtained bromophenol derivatives (6-26) were effective inhibitors of the cytosolic carbonic anhydrase I and II isoforms (hCA I and II) and acetylcholinesterase (AChE) enzymes with Ki values in the range of 7.8 ±â€¯0.9-58.3 ±â€¯10.3 nM for hCA I, 43.1 ±â€¯16.7-150.2 ±â€¯24.1 nM for hCA II, and 159.6 ±â€¯21.9-924.2 ±â€¯104.8 nM for AChE, respectively. Acetylcholinesterase inhibitors are the most popular drugs applied in the treatment of diseases such as Alzheimer's disease, Parkinson's disease, senile dementia, and ataxia, among others.

Synthesis of novel sulfamides incorporating phenethylamines and determination of their inhibition profiles against some metabolic enzymes.

A series of sulfamides were synthesized and evaluated for their acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and carbonic anhydrase inhibition properties. The synthesis of sulfamides was achieved by the reactions of phenethylamines with N,N-dimethylsulfamoyl chloride in the presence of Et3 N. The methoxylated sulfamides were converted into their phenolic derivatives with BBr3 for structure-activity relationships. The synthesized sulfamide/phenolic sulfamide derivatives were investigated as cholinesterase inhibitors and their relative role in AChE versus BChE inhibition was defined. Sulfamide/phenolic sulfamide derivatives are known as important carbonic anhydrase inhibitors; therefore, the synthesized compounds were investigated for inhibitory effects on both carbonic anhydrase isoenzymes. Additionally, we evaluated four different enzymes, which were inhibited in the low nanomolar range by these compounds. According to the present studies, for AChE, BChE, and carbonic anhydrase I and II, the ranges of results are recorded as 0.027-0.076 nM, 0.075-0.327 nM, 0.123-0.678 nM, and 0.024-0.688 nM, respectively.

Schiff bases and their amines: Synthesis and discovery of carbonic anhydrase and acetylcholinesterase enzymes inhibitors.

Three series of symmetrical Schiff bases were synthesized from 1,2-diaminoethane, 1,3-diaminopropane and 1,4-diaminobutane and substituted benzaldehydes, and reduced by sodium borohydride to the corresponding benzylic diamines 4-6. All of the compounds obtained were characterized using elemental analysis, FT-IR, 1 H NMR, and 13 C NMR spectroscopy. The enzyme inhibitory properties of these compounds were tested and the influence of the alkane chain length and the substituents on the phenyl group on the enzyme inhibition activity were examined. The novel Schiff bases and their amine derivatives (1a-d, 2a-d, 3b-d, 4a-c, 5a-c, 6a, 6c, 6d) were effective inhibitors of the cytosolic carbonic anhydrase I and II isoforms (hCA I and II), and acetylcholinesterase (AChE) with Ki values in the range of 159.43 ± 30.03 to 563.73 ± 115.30 nM for hCA I, 104.88 ± 18.44 to 524.32 ± 95.03 nM for hCA II, and 3.95 ± 0.74 to 30.83 ± 6.81 nM for AChE.

1H-indazole molecules reduced the activity of human erythrocytes carbonic anhydrase I and II isoenzymes.

Carbonic anhydrase (CA) is an important metabolic enzyme family closely related to many physiological and pathological processes. Currently, carbonic anhydrase inhibitors are the target molecules in the treatment and diagnosis of many diseases. In present study, we investigated the inhibitory effects of some indazole molecules on the CA-I and CA-II isoenzymes isolated from human erythrocytes. We showed that human CA-I and CA-II activities were reduced by of some indazoles at low concentrations. IC50 values, Ki constants, and inhibition types for each indazole molecule were determined. The indazoles showed Ki constants in a range of 0.383 ± 0.021 to 2.317 ± 0.644 mM, 0.409 ± 0.083 to 3.030 ± 0.711 mM against CA-I and CA-II, respectively. Each indazole molecule exhibited a noncompetitive inhibition effect. Bromine- and chlorine-bonded indazoles were found to be more potent inhibitory effects on carbonic anhydrase isoenzymes. In conclusion, we conclude that these results may be useful in the synthesis of carbonic anhydrase inhibitors.

Inhibitory properties of some heavy metals on carbonic anhydrase I and II isozymes activities purified from Van Lake fish (Chalcalburnus Tarichi) gill.

In this study, CA I and II isoenzymes were purified from Van Lake fish gills by using Sepharose-4B-L-tyrosine-sulfanilamide affinity chromatography and to determine the effects of some metals on the enzyme activities. For purified CA I isoenzyme, yield, specific activity, and purification fold were obtained as 42.07%, 4948.12 EU/mg protein, and 116.61 and for CA II isoenzyme, 7%, 1798.56 EU/mg protein, and 42.38 respectively. Activity of CA was determined by measuring "CO2-hydratase activity". Purity control was checked by SDS-PAGE. In vitro inhibitory effect of Cu2+, Ag+, Cd2+, Ni2+ metal ions, and arsenic (V) oxide were also examined for both isozymes activities. Whereas Cu2+, Ag+, Cd2+, and Ni2+ ions showed inhibitory effects on both isozymes, arsenic (V) oxide showed activation effect. IC50 values were calculated by drawing activity %-[I] graphs for metal ions exhibiting inhibitory effects. IC50 values were determined as 3.39, 6.38, 13.52, and 206 µM for CA I isozyme and 6.16, 20.29, 46, and 223 µM for CA II isozyme respectively.

The effects of ex vivo ozone treatment on human erythrocyte carbonic anhydrase enzyme.

Ozone autohemotherapy is used in the treatment of some diseases. Carbonic anhydrases (CAs, EC 4.2.1.1) are metalloenzymes and play a role in homeostatic mechanisms. The aim of this study was to investigate the effects of ozone on human red blood cell CA (hCA) enzyme activity. Blood samples were treated with different doses of ozone (10, 20, 30 µg/ml) and the erythrocyte total CA activities were determined. Also, purified hCAI and hCAII isozymes were treated with the same doses of ozone and the enzyme activities were measured. About 30 µg/ml ozone treatment decreased the purified hCAI and hCAII activity and increased the total CA activity compared to the control. Because the implication of CAs on many physiological and biochemical processes is linked to pathologies, it can be suggested that the ozone at a concentration of 30 µg/ml is safely used by autohaemotherapy in a well-designed clinical trial.

Enhancement of intrinsic fluorescence of human carbonic anhydrase II upon topiramate binding: Some evidence for drug-induced molecular contraction of the protein.

In this report, the effect of topiramate (TPM), an anticonvulsant sulfamate drug, on the structure of human carbonic anhydrase II (hCA II) was investigated by spectroscopic techniques. The intrinsic fluorescence experiments indicated that TPM binding causes enhancement of enzyme fluorescence via decreasing the internal quenching and energy transfer efficiency, the result supported by molecular dynamics simulation. Thermodynamic analysis of the binding process suggested that hydrogen bonding and van der Waals interactions are the major forces in the interaction of TPM with hCA II. The far-UV circular dichroism (CD) results showed that TPM caused increment in α-helical and ß-sheet content of hCA II whereas, near-UV CD experiments in the presence of the drug showed induction of some compactness in the enzyme tertiary structure. The number of accessible tryptophans and protein surface hydrophobicity index of the enzyme were reduced in the presence of TPM which confirms the enzyme structural compactness upon drug binding. In addition, the enzyme thermal stability was increased in the presence of the drug. It seems that the induction of compactness in the enzyme structure upon drug binding may be responsible for increment of its conformational stability.

Inhibition properties of some flavonoids on carbonic anhydrase I and II isoenzymes purified from human erythrocytes.

Carbonic anhydrases (CAs, E.C.4.2.1.1) play a critical role in many important physiological events and treatment of some diseases. Flavonoids or phenolic compounds have been discovered as novel CAs inhibitors instead of the traditional sulfonamides, with different binding to CAs, pro-drug activities, and new inhibition mechanisms. Here, we investigated the inhibition effects of some flavonoids including malvin, callistephin, oenin, pelargonin, silychristin, and 1-(4-methoxyphenyl)-2-methyl-3-nitro-1-H-indol-6-ol (ID-8) against hCA I and II, which purified from human erythrocytes by affinity column chromatography. Both hCA isoenzymes were inhibited by flavonoids, with IC50 and Ki values in the range of 2.34 nM to 346.5 µM and 51.01-99.55 µM for hCA I and 86.60-750.00 µM for hCA II, respectively. These results showed that flavonoids especially malvin and oenin effectively inhibited hCA I and II isoenzymes. Hence, they may be used as an effective CA inhibitor in medical applications for treatment of certain diseases such as glaucoma, in the future.

Synthesis, characterization and in vitro inhibition of metal complexes of pyrazole based sulfonamide on human erythrocyte carbonic anhydrase isozymes I and II.

Sulfonamides represent an important class of biologically active compounds. A sulfonamide possessing carbonic anhydrase (CA) inhibitory properties obtained from a pyrazole based sulfonamide, ethyl 1-(3-nitrophenyl)-5-phenyl-3-((5-sulfamoyl-1,3,4-thiadiazol-2-yl)carbamoyl)-1H-pyrazole-4-carboxylate (1), and its metal complexes with the Ni(II) for (2), Cu(II) for (3) and Zn(II) for (4) have been synthesized. The structures of metal complexes (2-4) were established on the basis of their elemental analysis, 1H NMR, IR, UV-Vis and MS spectral data. The inhibition of two human carbonic anhydrase (hCA, EC 4.2.1.1) isoenzymes I and II, with 1 and synthesized complexes (2-4) and acetazolamide (AAZ) as a control compound was investigated in vitro by using the hydratase and esterase assays. The complexes 2, 3 and 4 showed inhibition constant in the range 0.1460-0.3930 µM for hCA-I and 0.0740-0.0980 µM for hCA-II, and they had effective more inhibitory activity on hCA-I and hCA-II than corresponding free ligand 1 and than AAZ.

Synthesis, carbonic anhydrase I and II isoenzymes inhibition properties, and antibacterial activities of novel tetralone-based 1,4-benzothiazepine derivatives.

Benzothiazepine compounds have a wide range of applications such as antibacterial, antidepressants, anticonvulsants, antihypertensives, antibiotics, antifungal, hypnotic, enzyme inhibitors, antitumor, anticancer and anti-HIV agents. In this study, the synthesis of novel tetralone-based benzothiazepine derivatives (1-16) and their in vitro antibacterial activity and human carbonic anhydrase isoenzymes I and II (hCA I and II) inhibitory effects were investigated. Both isoenzymes were purified by sepharose-4B-l-tyrosine-sulfanilamide affinity chromatography from fresh human red blood cells. All compounds demonstrated the low nanomolar inhibitory effects on both isoenzymes using esterase activity. Benzothiazepine derivative 2 demonstrated the best hCA I inhibitory effect with Ki value of 18.19 nM. Also, benzothiazepine derivative 7 showed the best hCA II inhibitory effect with Ki value of 11.31 nM. On the other hand, acetazolamide clinically used as CA inhibitor, showed Ki value of 19.92 nM against hCA I and 33.60 nM against hCA II, respectively.

Synthesis of diaryl ethers with acetylcholinesterase, butyrylcholinesterase and carbonic anhydrase inhibitory actions.

A series of diaryl ethers were synthesized and their human (h) carbonic anhydrase (CA) isoenzymes hCA I and II, acetylcholinesterase (AChE), and butyrylcholinesterase (BuChE) inhibitory actions were investigated. The new compounds were synthesized from the corresponding phenols and bromobenzenes via the Ullmann reaction, by using dipicolinic acid as a copper (I) complexing ligand. hCA I and II were inhibited with Kis in the low nanomolar range of 102.01-127.13 nM against hCA I, and of 73.71-113.40 nM against hCA II, whereas the inhibition constants against AChE were of 15.35-18.34 nM and against BChE in the range of 9.07-22.90 nM. The CA inhibition mechanism with these ethers is unknown, but may be similar to that of aryl methyl ethers investigated earlier by computational approaches.

Synthesis of two phloroglucinol derivatives with cinnamyl moieties as inhibitors of the carbonic anhydrase isozymes I and II: an in vitro study.

Two cinnamyl-substituted phloroglucinols, 4-p-methoxycinnamyl phloroglucinol (9) and 4,6-bis-p-methoxycinnamyl phloroglucinol (10) were synthesized. Two carbonic anhydrases, human carbonic anhydrase I and II (hCA I and II), were purified. Kinetic interactions between these isozymes with 9 and 10 were investigated. These new compounds exhibited inhibitory effects on the hCA I and II enzymes' activity in vitro. The combination of the inhibitory effects of both phloroglucinol and p-coumaric acid groups in a single compound was explored. However, relative to the inhibitory effects of the two groups separately, compounds 9 and 10 demonstrated comparable inhibitory effects. More effective inhibitors of CAs could be created by testing these compounds on other CA isozymes.

Investigation of the Effect of Some Optically Active Imine Compounds on the Enzyme Activities of hCA-I and hCA-II under In Vitro Conditions: An Experimental and Theoretical Study.

Inhibitors of carbonic anhydrase (hCA; EC 4.2.1.1) are used as medicines for many diseases. Therefore, they are very important. In this study, a known series of Schiff bases were synthesized and their effects on the activities of hCA-I and hCA-II, which are cytosolic isoenzymes of carbonic anhydrase, were investigated under in vitro conditions. The synthesized compounds (H1, H2, H3, and H4) were found to cause inhibition on enzyme activities of hCA-1 and hCA-II. IC50 values of H1, H2, H3, and H4 compounds were 140, 88, 201, and 271 µM for hCA-I enzyme activity and 134, 251, 79, and 604 µM for hCA-II enzyme activity, respectively. The synthesized Schiff bases were characterized by several methods, including (1) H NMR, FT-IR, elemental analysis, and polarimetric measurements. Correlation coefficient square values (R(2) ) of comparison of the theoretical and experimental (1) H NMR shifts for H1, H2, H3, and H4 compounds were found as 0.9781, 0.9814, 0.9758, and 0.8635, respectively.

Carbonic anhydrase inhibitors: Design, synthesis, kinetic, docking and molecular dynamics analysis of novel glycine and phenylalanine sulfonamide derivatives.

The inhibition of two human cytosolic carbonic anhydrase isozymes I and II, with some novel glycine and phenylalanine sulfonamide derivatives were investigated. Newly synthesized compounds G1-4 and P1-4 showed effective inhibition profiles with KI values in the range of 14.66-315µM for hCA I and of 18.31-143.8µM against hCA II, respectively. In order to investigate the binding mechanisms of these inhibitors, in silico docking studies were applied. Atomistic molecular dynamic simulations were performed for docking poses which utilize to illustrate the inhibition mechanism of used inhibitors into active site of CAII. These sulfonamide containing compounds generally were competitive inhibitors with 4-nitrophenylacetate as substrate. Some investigated compounds here showed effective hCA II inhibitory effects, in the same range as the clinically used sulfonamide, sulfanilamide or mafenide and might be used as leads for generating enzyme inhibitors possibly targeting other CA isoforms which have not been yet assayed for their interactions with such agents.

Synthesis of 3,4-dihydroxypyrrolidine-2,5-dione and 3,5-dihydroxybenzoic acid derivatives and evaluation of the carbonic anhydrase I and II inhibition.

The inhibition of two human cytosolic carbonic anhydrase (hCA, EC 4.2.1.1) isozymes I and II, with some 3,4-dihydroxypyrrolidine-2,5-dione and 3,5-dihydroxybenzoic acid derivatives, were investigated by using the esterase assay, with 4-nitrophenyl acetate (4-NPA) as substrate. Compounds 10-13 showed KI values in the range of 112.7-441.5 µM for hCA I and of 3.5-10.76 µM against hCA II, respectively. These hydroxyl group containing compounds generally were competitive inhibitors. Some hydroxyl group containing compounds investigated here showed effective hCA II inhibitory effects, in the same range as the clinically used sulfonamide acetazolamide, and might be used as leads for generating enzyme inhibitors possibly targeting other CA isoforms which have not been yet assayed for their interactions with such agents.

Synthesis and evaluation of N-heteroarylsubstituted triazolosulfonamides as carbonic anhydrase inhibitors.

A new series of N-heteroarylsubstituted triazolosulfonamide compounds were synthesized and their inhibitory effects on the activity of purified human carbonic anhydrase (hCA) I and II were evaluated. Compounds (3 a-k) were prepared by propargylation of N-heteroaryl compounds. Compound 5 was obtained from sulfanilamide and sodium nitrite followed by addition of sodium azide. The products (6 a-k) were synthesized from compounds 3 and 5. The results showed that all the synthesized compounds were inhibited the CA isoenzymes activity. Figure 6a (IC50 = 0.52 µM for hCA I and 0.34 µM for hCA II) has the most inhibitory effect among the synthesized compounds.

Synthesis and Biological Potential Assessment of 2-Substituted Quinazolin-4(3H)-ones as Inhibitors of Phosphodiesterase-I and Carbonic Anhydrase-II.

A library of twenty-five derivatives of 2-substituted quinazolin-4(3H)-ones 1-25 was synthesized and evaluated against phosphodiesterase-I (PDE) and carbonic anhydrase-II (CA). Compounds 17 (IC50 = 210.7 ± 2.62 µM), 16 (IC50 = 301.6 ± 1.18 µM), and 13 (IC50 = 458.13 ± 3.60 µM), selectively exhibited PDE inhibition while compounds 22 (IC50 = 61.33 ± 2.38 µM), 1 (IC50 = 108.30 ± 0.93 µM), and 21 (IC50 = 191.93 ± 2.72 µM), discriminatingly exhibited CA inhibition as compared to standards EDTA (IC50 = 277.69 ± 2.52 µM) and acetazolamide (IC50 = 0.12 ± 0.03 µM), for PDE and CA inhibitions, respectively. However, compound 15 was found to be active against both enzymes with the IC50 values 344.33 ± 4.32 µM and 20.94 ± 0.58 µM, for PDE and CA inhibitions, respectively. Remaining compounds were found to be inactive against both the enzymes. Structure-activity relationship studies are discussed herein.