Synthesis,characterization and carbonic anhydrase inhibitory activity of novel benzothiazole derivatives

N-protected amino acids were reacted with substituted benzothiazoles to give the corresponding N-protected amino acid-benzothiazole conjugates (60–89%). Their structures were confirmed by proton nuclear magnetic resonance (¹H NMR), carbon-13 nuclear magnetic resonance (¹³C NMR), IR and elemental analysis. Their carbonic anhydrase (CA, EC 4.2.1.1) inhibitory activities were determined against two cytosolic human isoforms (hCA I and hCA II), one membrane-associated (hCA IV) and one transmembrane (hCA XII) enzyme by a stopped-flow CO₂ hydrase assay method. The new compounds showed rather weak, micromolar inhibitory activity against most of these enzymes.     

Sequential resonance assignments in protein 1H nuclear magnetic resonance spectra. Basic pancreatic trypsin inhibitor

The assignment of the ¹H nuclear magnetic resonance spectrum of the basic pancreatic trypsin inhibitor with the use of two-dimensional ¹H nuclear magnetic resonance techniques at 500 MHz is described. The assignments are based entirely on the known amino acid sequence and the nuclear magnetic resonance data. Individual resonance assignments were obtained for all backbone and C^β protons, with the exception of those of Arg1, Pro2, Pro13 and the amide proton of Gly37. The side-chain resonance assignments are complete, with the exception of Pro2 and Pro13, the N^δ protons of Asn44 and the peripheral protons of the lysine residues and all but two of the arginine residues.     

Nuclear magnetic resonance studies on oligo-deoxyribonucleotides containing thedam methylation site GATC. Adenine methylation of d(GGATCC) does not change the helix geometry

We have studied the conformation of two hexanucleotides d(GGATCC) and d(GGm⁶ATCC) using proton nuclear magnetic resonance. Nuclear Overhauser effect measurements show that d(GGATCC) assumes a normal right handed B helix. The single and double strand resonances are in fast exchange on a proton nuclear magnetic resonance time scale. For d(GGm⁶ATCC), up to the Tm separate resonances are observed for each state, indicating slow exchange, though above the Tm it becomes more rapid. The orientation of the adenosine methyl-amino group, preferentiallycis to N¹, hinders base pair formation.The connectivities of the resonances of the two states were established by saturation transfer experiments. At 0°C irradiation of the m⁶ A-T imino proton gives an nuclear Overhauser effect to AH² showing that base pairing is Watson-Crick. Intra and interresidue nuclear Overhauser effects starting from the 3′ terminus show that the helix is right handed and in the B-form.The results on the two oligomers demonstrate that adenosine methylation induces little or no change in the conformation of the helix, but reduces the Tm from 45° to 32°C and slows the opening and closing of the m₆A.T base pair by a factor of about 100.     

Determination of the structure of sulfated tetra- and pentasaccharides obtained by alkaline borohydride degradation of hen ovomucin. A fast atom bombardment-mass spectrometric and1H-NMR spectroscopic study

Alkaline borohydride reductive cleavage of hen ovomucin resulted in the release of a series of neutral and acidic oligosaccharide-alditols.¹H-NMR spectroscopy in combination with fast ion bombardment-mass spectrometry in negative ion mode were used for investigation of the structures of three oligosaccharide-alditols. The following structures were established: Abbreviations NeuAc N-acetyl-d-neuraminic acid - Gal d-galactose - GlcNAc N-acetyl-d-glucosamine - Gal-NAc-ol N-acetyl-d-galactosaminitol - NMR nuclear magnetic resonance - FAB-MS fast atom bombardmentmass spectrometry     

Detection and characterization of acidic compartments (vacuoles) in Chlorella vulgaris 11h cells by 31P-in vivo NMR spectroscopy and cytochemical techniques

Acidic inorganic phosphate (Pi) pool (pH around 6) was detected besides the cytoplasmic pool in intact cells of Chlorella vulgaris 11h by ³¹P-in vivo nuclear magnetic resonance (NMR) spectroscopy. It was characterized as acidic compartments (vacuoles) in combination with the cytochemical technique; staining the cells with neutral red and chloroquine which are known as basic reagents specifically accumulated in acidic compartments. Under various conditions, the results obtained with the cytochemical methods were well correlated with those obtained from in vivo NMR spectra; the vacuoles were well developed in the cells at the stationary growth phase where the acidic Pi signal was detected. In contrast, cells at the logarithmic phase in which no acidic Pi signal was detected contained only smaller vesicles that accumulated these basic reagents. No acidic compartment was detected by both cytochemical technique and ³¹P-NMR spectroscopy when the cells were treated with NH₄OH. The vacuolar pH was lowered by the anaerobic treatment of the cells in the presence of glucose, while it was not affected by the external pH during the preincubation ranging from 3 to 10. Possible vacuolar functions in unicellular algae especially with respect to intracellular pH regulation are discussed.Non-standard abbreviations EDTA ethylenediaminetetraacetic acid - HEPES N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid - MDP methylene diphosphonic acid - NMR nuelear magnetic resonance - PCA perchloric acid - PCV packed cell volume - Pi inorganic phosphate - Pic sytoplasmic inorganic phosphate - Piv vacuolar inorganic phosphate - ppm parts per million - SP sugar phosphates - TCA trichloroacetic acid     

A proton nuclear magnetic resonance study of the physical changes in growing plant cell walls

Changes in broadline proton nuclear magnetic resonance parameters of cell walls during growth of etiolated hypocotyls of bean (Phaseolus vulgaris L.) indicate that cell wall structure becomes more rigid during development. Most of the changes are completed in the first 6 cm below cotyledon insertion and are correlated with increased restriction of proton movements in regions of dense polymer packing.Abbreviations FID free induction decay - M₂ second moment - M_2interpair interpair second moment - NMR nuclear magnetic resonance - T_1D dipolar relaxation time - T₂ spin-spin relaxation time This work was supported by grants from Natural Sciences and Engineering Research Council of Canada to A.L.M., I.E.P.T. and M. Bloom.     

Structure of methylmenaquinone-7 isolated fromAlteromonas putrefaciens IAM 12079

The structure of methylmenaquinone-7, a major component of methylmenaquinones isolated fromAlteromonas putrefaciens IAM 12079, was determined by comparing the proton nuclear magnetic resonance (¹H-NMR) spectrum of its chromenyl derivative with those of menachromenyl acetate prepared from menaquinone-7 and phyllochromenyl acetate. Based on the numbering system used for naphthopyrane nucleus, proton signals of the 7- and 10-position for chromenyl derivatives were assigned from the signals on the¹H-NMR spectra phyllochromenyl acetate and phyllochromenol. As a result, the chemical structure of methylmenaquinone-7 was determined as 2,8-dimethyl-3-farnesylgeranygeranyl-1,4-naphthoquinone.     

Sequential resonance assignments in protein 1H nuclear magnetic resonance spectra: Glucagon bound to perdeuterated dodecylphosphocholine micelles

The assignment of the ¹H nuclear magnetic resonance spectrum of glucagon bound to perdeuterated dodecylphosphocholine micelles with the use of two-dimensional ¹H nuclear magnetic resonance techniques at 360 MHz is described. Sequential resonance assignments were obtained for all backbone and C^β protons except the N-terminal amino group and the amide proton of Ser2. The assignments of the non-labile amino acid side-chain protons are complete except for the γ-methylene protons of Gln20 and Gln24. These assignments provide a basis for the determination of the three-dimensional structure of lipid-bound glucagon.     

Structural characterization of blood group A glycosphingolipids recognized by the antibody 3G9-A

In this study, the antibody 3G9-A was assayed for activity against human erythrocyte glycosphingolipids. The antibody was found to recognize glycosphingolipid components from blood group A erythrocytes but not glycosphingolipids from blood group B or O erythrocytes. Subsequent investigation revealed that the glycosphingolipid components recognized by the antibody were also recognized by a blood group A specific monoclonal antibody. The structures of two of the isolated active glycosphingolipid components were structurally characterized using proteon nuclear magnetic resonance (¹H NMR) and gas chromatography-mass spectrometry (GC-MS) techniques and were found to consist of two blood group A glycosphingolipids; the type 2 chain A^b and type 3 chain A^a glycosphingolipids. Subsequent analysis of the remaining active components by GC-MS and immunostaining techniques revealed that all of the active components were blood group A glycosphingolipids. Furthermore, structural studies of the active components suggested that the epitope of the antibody consisted of the group A trisaccharide, GalNAc1,3(Fuc1,2)Gal.Abbreviations GC-MS gas chromatography-mass spectrometry - ¹H NMR proton nuclear magnetic resonance - Gal d-galactose - Glc d-glucose - Fuc l-fucose - GalNAc N-acetylgalactosamine - GlcNAc N-acetylglucosamine - Cer ceramide - mAb monoclonal antibody - BSA bovine serum albumin - PBS phosphate buffered saline - FID free induction decay - PMAA partially methylated alditol acetates     

Synthesis of some novel 2-substituted benzothiazole derivatives containing benzylamine moiety as monoamine oxidase inhibitory agents

In the present work, 12 new 2-(5-substituted-benzothiazol-2-ylsulfanyl)-N-(substitutedbenzyl)-N-(4-substitutedphenyl) acetamide derivatives (4a–l) was designed and synthesized. The structures of the synthesized compounds were clarified using Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (¹H-NMR), carbon-13 nuclear magnetic resonance (¹³C-NMR) and high-resolution mass spectrometry (HRMS) spectral data. Purity of synthesized compounds was checked by high-performance liquid chromatography (HPLC) analyses and purity ratio was found between 96.5–99.9%. The inhibitory activity of the compounds against MAO-A and MAO-B enzymes was evaluated by using in vitro flurometric method in which kynuramine was used as a substrate. Most of the compounds exhibited more selective inhibitory activity towards monoamine oxidase B (MAO-B) than monoamine oxidase A (MAO-A). Compound 4h was determined as the most potent compound against both enzyme types. The MAO-B enzyme kinetic of the compound 4h was studied and nature of MAO-B inhibition, caused by this compound, was investigated. The graphical analysis of steady-state inhibition data indicated that compound 4h is a mixed type inhibitor. Theoretical calculation of absorption, distribution, metabolism, excretion (ADME) properties for the synthesized compounds was also carried out and observed data supported the potential of compound 4h.     

1H and 13c nmr analysis of lycorine and α-dihydrolycorine

-The ¹H and ¹³C NMR spectra of lycorine and its α-dihydro derivative have been studied. The employment of nuclear magnetic double resonance, nuclear Overhauser effect and acetylated derivatives, allows the assignment of all proton resonances. The assignments of the carbon shifts have been obtained by means of proton noise decoupled, single frequency off-resonance decoupled, single frequency selective decoupling, time dependence nuclear Overhauser effect and by comparison with reference compounds.     

Fruiting of Schizophyllum commune Induced by Certain Ceramides and Cerebrosides from Penicillium funiculosum

Fruiting bodies were formed around a Penicillium colony which appeared as a contaminant in a culture of Schizophyllum commune, and this phenomenon was reproduced with a synthesized system consisting of S. commune IAM 9006 and P. funiculosum A-l. The active substances were recovered in an acetone extract of the mycelia of P. funiculosum, purified by silica gel column chromatography and reverse-phase high-performance liquid chromatography, and characterized by infrared spectroscopy, gas-liquid chromatography, gas-liquid chromatography-mass spectroscopy and nuclear magnetic resonance spectroscopy. They were ceramides and cerebrosides having nonadecasphingadienine and 2-hydroxy fatty acid moieties in common. The major component was identified as (4E,8E)-N-2^′-hydroxy-(E)-3^′-octadecenoyl-1-O-β-glucopyranosyl-9-methyl-4,8-sphingadienine.     

Quantitative evaluation of NMR and MRI methods to measure sucrose concentrations in plants

Summary Developing pea (Pisum sativum L.) seeds were chosen to evaluate the performance of various nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) methods of detecting sucrose in plants. The methods included chemical shift selective imaging (CHESS), heteronuclear correlation via¹³C-¹H coupling (HMQC), and homonuclear correlation via¹H-¹H coupling (DQF). The same experiments were also performed on sucrose phantom samples to evaluate the methods in the absence of the line broadening observed in plant systems. Using the spin echo technique for multi-slice imaging, we could discern the detailed internal structure of the intact seed with a resolution of tens of microns. The proton spin-lattice relaxation time and linewidth as a function of the age of the seed were measured to optimize the efficiency of the NMR and MR experiments. The age-dependent changes in these NMR parameters are consistent with the accumulation of insoluble starch as age increases. Both the NMR and MRI results are in accord with the results of chemical analysis, which reveal that the sucrose concentration is higher in the embryo than in the seed coat, and glucose is at low concentration throughout the seed. Of the three methods for proton observation, the enhanced version of the CHESS approach (CD-CHESS) provides the best combination of sucrose detection and water suppression. Direct observation of¹³C is preferable to indirect detection using HMQC because of water signal bleed-through in samples with large (>200 Hz) linewidths.Abbreviations CD-CHESS continuous wave decoupling chemical shift selective imaging - CHESS chemical shift selective imaging - CSI chemical shift imaging - CW continuous wave - DQF homonuclear double quantum filtering - FOV field of view - FW fresh weight - GHMQC gradient version of the heteronuclear multiple quantum coherence     

High resolution nuclear magnetic resonance studies of the active site of chymotrypsin. I. The hydrogen bonded protons of the "charge relay" system

High resolution proton nuclear magnetic resonance has been used to observe protons at the active site of chymotrypsin A_δ and at the same region of chymotrypsinogen A. A single resonance with the intensity of one proton is located in the low field region of the nuclear magnetic resonance spectrum. This resonance is observed in H₂O solutions but not in ²H₂O. On going from low to high pH the resonance titrates upfield 3 parts per million in both proteins and has a pK of 7.5. The titration can be prevented by alkylating His57 with either of two active site directed chloromethyl ketones. Using these data the proton resonance has been assigned to a proton in a hydrogen bond between His57 and Asp102. Further confirmation of this assignment lies in the observation of a similar resonance in this same low field region of the nuclear magnetic resonance spectrum of trypsin, trypsinogen, subtilisin BPN′ and α-lytic protease all of which have the Asp-His-Ser triad at their active sites.This proton resonance in chymotrypsin A_δ was used as a probe to monitor the charge state of the active site upon formation of a stable acyl-enzyme analogue N²(N-acetylalanyl)-N¹benzoylcarbazoyl-chymotrypsin A_δ. In this derivative the His-Asp proton resonance titrates from the same low pH end point as in the native enzyme, ?18 parts per million, to a new high pH end point of ?14.4 parts per million (versus ?15.0 parts per million in the native enzyme). The difference of 0.6 parts per million in the high pH end points between the native and acyl enzyme is interpreted as supporting the suggestion that a hydrogen bond exists between Ser195 and His57 in the native enzyme and zymogen.We conclude from these studies that the charge relay system from Asp102 across His57 to Ser195 is intact in chymotrypsin A_δ and chymotrypsinogen A, and that, in the native enzyme, it slightly polarizes Ser195.     

Structure and function of haemoglobin philly (Tyr C1 (35) β→Phe)

We have purified haemoglobin Philly by isoelectric focusing on polyacrylamide gel, and studied its oxygen equilibrium, proton nuclear magnetic resonance spectra, mechanical stability, and pH-dependent u.v. difference spectrum. Stripped haemoglobin Philly binds oxygen non-co-operatively with high affinity. Inorganic phosphate and 2,3-diphosphoglycerate have little effect on the equilibrium curve, but inositol hexaphosphate lowers the affinity and induces co-operativity. These properties are explained by the nuclear magnetic resonance spectra which show that stripped deoxyhaemoglobin Philly has the quaternary oxy structure and that inositol hexaphosphate converts it to the deoxy structure. An exchangeable proton resonance at ?8.3 p.p.m. from water, which is present in oxy- and deoxyhaemoglobin A, is absent in both these derivatives of haemoglobin Philly and can therefore be assigned to one of the hydrogen bonds made by tyrosine C1-(35)β, probably the one to aspartate H8(126)α at the α₁β₁ contact. Haemoglobin Philly shows the same pH-dependent u.v. difference spectrum as haemoglobin A, only weaker, so that a tyrosine other than 35β must be mainly responsible for this.     

13C nmr study of the helix–coil transition of poly-N5-(3-hydroxypropyl)-L-glutamine

The helix–coil transition of poly-N⁵-(3-hydroxypropyl)-L -glutamine in methanol–water solutions has been observed using ¹³C nuclear magnetic resonance. Two signals appear in the α-CH region in the course of the transition; this is in contrast with previous proton magnetic resonance experiments carried out on this polymer in the same solvent system.     

Metabolism of auxin in pine tissues: Indole-3-acetic acid conjugation

Incubation of sections of various tissues of Pinus pinea L. with a relatively low concentration (3.6 μM) of indole-3-acetic acid-2-¹⁴C (IAA) resulted in the formation of two major metabolites. The first, which has not been identified, seemed to be a polar acidic compound and the second was identified as indole-3-acetylaspartic acid (IAAsp). The polar acidic metabolite has been found to be the major metabolite in needles, shoot wood and roots, while IAAsp has been found to be the major metabolite in shoot bark. Increasing the concentration of IAA in the incubation medium resulted in an increase in the formation of a third metabolite which proved to be l-O-(indole-3-acetyl)-β-d -glucose (IAGlu) and a concomitant decrease in the amount of the polar acidic metabolite. This phenomenon was prominent particularly in needles. IAGlu was isolated from needles and IAAsp was isolated from shoot bark by means of polyvinylpolypyrrolidone column chromatography and preparative thin-layer chromatography. IAGlu was identified by comparison with authentic material by co-chromatography in three different solvent systems and by ¹H-nuclear magnetic resonance analysis. IAAsp was identified by comparison with authentic material by gas-liquid chromatography and ¹H-nuclear magnetic resonance analysis. Several aspects of formation, separation and isolation of IAA metabolites are discussed.     

A structural study of the asparagine-linked oligosaccharide moiety of duck ovomucoid

Asparagine-linked oligosaccharides of duck ovomucoid were released quantitatively from the protein by digestion with glycoamidase A (from almond), the reducing ends of the oligosaccharide chains thus obtained were aminated with a fluorescent reagent, 2-aminopyridine, and the mixture of pyridylamino derivatives of the oligosaccharides was separated using two different types of high performance liquid chromatography (HPLC) on a reversed phase column and an amide adsorption column. More than sixteen different oligosaccharides were separated and the structures were characterized by a combination of the 2-dimensional sugar mapping technique using HPLC, exoglycosidase digestion, and proton nuclear magnetic resonance measurements (1- and 2-dimensional). Furthermore, the HPLC profile of duck ovomucoid oligosaccharides was compared with previously reported profiles obtained from quail and chicken ovomucoids.Abbreviations COSY chemical shift-correlated spectroscopy - DQF-COSY double quantum filtered COSY - DSS sodium, 4,4-dimethyl-4-silapentane 1-sulfonate - Gal D-galactose - GlcNAc or GN N-acetyl-D-glucosamine - HOHAHA homonuclear Hartmann-Hahn spectroscopy - Man or M D-mannose - NOE nuclear Overhauser enhancement - ODS octadecylsilyl - PA pyridylamino - ROESY rotating frame nuclear Overhauser effect spectroscopy - SDS/PAGE sodium dodecyl sulfate/polyacrylamide gel electrophoresis     

Biotransformation of 5-en-3β-ol steroids by Mucor circinelloides lusitanicus

In this work, we report the mode of biotransformation of 5-en-3β-ol steroids using Mucor circinelloides lusitanicus for the first time. Here, we selected seven 5-en-3β-ol steroids as substrates. The main characteristic of the fungus was to introduce a 7α-hydroxyl group into substrates 1--5. With substrate 2, 3β, 7α, 11α-trihydroxypregna-5-en-20-one (2b) was obtained as the final product in good yield (46.4%). All the metabolites were determined by infrared spectra, high-resolution mass spectrometry, proton nuclear magnetic resonance, and carbon-13 nuclear magnetic resonance.     

Mechanisms of transmembrane cation transport studied by nuclear magnetic resonance spectroscopy

Several molecules like ionophores, vitamins, ion-binding cyclic peptides, acidic phospholipids, surfactants are known to expose the inner side of vesicles, to the externally added cations. Whereas ionophores and certain other systems bring about these changes by a selective transport (influx) of the cation by specialized mechanisms known as the carrier and channel mechanism, other systems cause lysis and vesicle fusion. These systems have been successfully studied using¹H,³¹ P and¹³C nuclear magnetic resonance spectroscopy after the demonstration, fifteen years ago, of the ability of paramagnetic lanthanide ions to distinguish the inside of the vesicle from the outside. The results of these ’nuclear magnetic resonance kinetics’ experiments are reviewed.