Characterization of proteins separated by displacement chromatography using low angle laser light scattering photometry

Summary -Lactoglobulin A and B (-LACT) were separated by displacement chromatography (DSC) on an ionexchange column using dextran sulfate as the displacer. A LALLS photometer and a UV detector, in series, were used to determine the molecular weight (MW) of the proteins, on-line. The results indicate that both, -LACT A and B, were present as dimers in the buffer used for the mobile phase. The MWs of the proteins were about 6–8% higher than the theoretical MW of a dimer (37,000). Additional control studies have shown the presence of a high molecular weight species in both the proteins, which could possibly be an aggregate. This species was observed in the LALLS signal but was nearly absent in the UV signal. Our work has demonstrated the feasibility of interfacing LALLS with displacement chromatography for detecting impurities or aggregates which may be difficult to detect by conventional detectors used for chromatography.     

Interfacing gradient elution ion-exchange chromatography and low-angle laser light-scattering photometry for analysis of proteins.

Molecular weights (MWs) of different proteins were determined by interfacing gradient elution ion-exchange chromatography and low-angle laser light-scattering photometry (IEC-LALLS). A high-performance strong cation-exchange column was used to elute proteins using fast (5 min) and conventional (15-30 min) gradients. The eluted proteins were characterized on-line by determining their MWs using LALLS. The specific refractive index (RI) increment (dn/dc) and the RI of the solvent used over the gradient range were determined off-line and used to calculate the absolute weight-average MWs. Four proteins, ribonuclease A, alpha-chymotrypsinogen A, trypsinogen and beta-lactoglobulin A (beta-LACT) were studied. Accurate MWs were obtained for all the proteins using fast and conventional gradients, except for beta-LACT, which aggregated as a function of the gradient employed. The degree of aggregation of beta-LACT increased as the rapidity of the gradient was increased over a fixed gradient range. This study indicated that it is possible to separate and characterize proteins rapidly using IEC-LALLS.     

Synthesis and properties of some chromium(III) β-diketonate complexes

Summary Equimolar quantities of CrCl₃ · 3THF and-diketones, -dkH, react to yield CrCl₂(-dk) · 2THF and CrCl₂(-dk) · THF complexes in coordinating and noncoordinating solvents respectively. For 1 : 2 and 1 : 3 molar ratios of reactants, derivatives of general formulae CrCl(-dk)₂ and Cr(-dk)₃ (where-dkH = acerylacetrrnc, benzoylacetonc and dibenzoylmethane) have been isolated. All complexes have been characterized by elemental analysis, molecular weights and by i.r. spectra.     

Spin probe studies on high temperature (T >T g) microdynamics of polyamide 66 fibers

Summary Short-range segmental motions of the amorphous phase of polyamide 66 were studied by means of spin probe radicals. In a dry sample the relaxation in the temperature range 366–426 with an activation energy 27.6 kJ/mol was found. In a sample containing traces of water two processes, and relaxations, with activation energies 47.0 kJ/mol and 22.0 kJ/mol, respectively, were found. relaxation was dominant in the higher temperature range (410–460 K) while relaxation was active at lower temperatures (365–410 K).

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Zusammenfassung Die inneren, lokalen Drehbewegungen in den amorphen Bereichen des Polyamid 66 wurden mit Hilfe der Paramagnersondenmethode untersucht. Wasserfreies Polyamid 66 zeigt den-Relaxations-prozeß (die Aktivierungsenergie 27.6 kJ/Mol) im Temperaturbereich von 366 K bis 426 K, wasserhaltiges Polyamid 66 zeigt zwei Prozesse,- und-Relaxationen, deren Aktivierungsenergien 47.0 kJ/Mol und 22.0 kJ/Mol sind. Die-Relaxation dominiert in dem höheren Temperaturbereich (von 410 K bis 460 K) und die-Relaxation in dem niederen Temperaturbereich (von 365 K bis 410 K).

     

Controlled-potential coulometric studies on fluoride and sulphate complexes of neptunium (VI)

Fluoride and sulphate complexing of Np(VI) has been studied by controlled-potential coulometry at a constant ionic strength. The values of ₁ ^* and ₂ ^* for fluoride complexes were found to be 9.4 and 8.9, respectively, at an ionic strength =0.5. At an ionic strength =1.0, ₁ ^* and ₂ ^* obtained were 6.6 and 10.5, respectively. Sulphate complexing of Np(VI) was studied only at an ionic strength =0.5. The value of ₁ ^* obtained was 5.6.     

Triterpene glycosides of Pulsatilla dahurica structures of glycosides A,B, C,and D

The isolation of four triterpene glycosides from the roots of the dahurian anemonePulsatilla dahurica (Fisch. ex DC) Spreng, is described together with their identification, on the basis of chemical transformations, spectral characteristics, and literature analogies, as hederagenin 3-O--L-arabinoside, hederagenin 3-O-[O--D-glucopyranosyl-(12)--L-arabinopyranoside], hederagenin 3-O--L-arabinopyranoside 28-O-[O--L-rhamnopyranosyl-(14)--D-glucopyranosyl-(16)--D-glucopyranoside], and hederagenin 3-O-[O--D-glucopyranosyl-(14)--L-arabinopyranoside] 28-O-[O--L-rhamnopyranosyl-(14)--D-glucopyranosyl-(16)--D-glucopyranoside].Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Branch, Russian Academy of Sciences, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, Nos. 3,4, pp. 349–356, May–August, 1992.     

Synthesis and transformations of 1-(4-hydroxyphenyl)dihydrouracils

N-(4-Hydroxyphenyl)--alanine and its methyl derivatives, as well as p-hydroxyphenylamino-, '-dipropionic acid, were obtained by the reaction of p-aminophenol with methyl acrylate and acrylic, methacrylic, and crotonic acids. The -alanines were converted to the corresponding hydrazides and 1-(4-hydroxyphenyl)dihydro- and thiodihydrouracils, which were decyclized by the action of alkalis to ureido and thioureido acids and were dehydrogenated by heating with sulfur to give uracils. The dihydro- and thiodihydrouracils were alkylated and acetylated.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1400–1406, October, 1982.     

Cyanoethylation of 2,5-dimethyltetrahydro-4-thiopyranone isomers and selective reduction of 2,5-dimethyl-5-(β-cyanoethyl)tetrahydro-4-thiopyranone and — 4-pi pe ridone

It has been found that only the cis isomer (liquid) of 2,5-dimethyltetrahydro-4-thiopyranone is cyanoethylated under the usual conditions. 2,5-Dimethyl-5-(-carboxyethyl)tetrahydro-4-thiopyranone was synthesized by the acid hydrolysis of 2,5-dimethyl-5-(-cyanoethyl)-tetrahydro-4-thiopyranone. The selective reduction with aluminum isopropoxide of 2,5-dimethyl-5-(-eyanoethyl) tetrahydro-4-thiopyranone and of the individual isomers of 2,5-dimethyl-5-(-cyanoethyl)-4-piperidone gave the isomeric 2,5-dimethyl-5-(-cyanoethyl)-tetrahydro-4-thiopyranols and -4-piperidols. The reaction of the isomeric 5-cyanoethyl-4-piperidols with allyl bromide gave the corresponding 1-allyl-2,5-dimethyl-5(-cyanoethyl)-4-piperidols.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 12–14, January, 1972.     

Triterpene glycosides ofPatrinia scabiosofolia; II

Conclusions The triterpene glycosides scabiosides D, E, F, and G have been isolated from the roots ofPatrinia scabiosofolia Fisch. et Link. It has been established that scabioside D is O--D-glucopyranosyl-(1 4)-O--L-arabopyranosyl-(1 3)-O-oleanoloyl-(28 1)--D-xylopyranose, and scabioside E is O--D-glucopyranosyl-(1 4)-O--L-arabopyranosyl-(1 3)-O-oleanoloyl-(28 1)-O--D-xylopyranosyl-(4 1)--L-rhamnopyranose.     

Triterpene glycosides ofAstragalus and their genins XLIX. Structures of cycloalpigenin C and cycloalpioside C

The structures of the new cycloartane triterpenoid cycloalpigenin C and its glycoside cycloalpioside C, isolated from the epigeal pan of Astragalus alopecurus Pall. (Leguminosae), have been determined. Cycloalpigenin C is 20R, 24S-epoxycycloartane-3,12,16, 25-tetraol, and cycloalpioside C is the 3-O- D-xylopyranoside of cycloalpigenin C.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 89 14 75. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 88–95, January–February, 1995. Original article submitted October 25, 1994.     

Steroids of the furostan and spirostan series from Nolina microcarpa II. structures of nolinospiroside D and nolinofurosides D, E, and F

Proofs are given of the structures of two new glycosides of the furostan series isolated from the leaves of the plantNolina microscarpa S. Wats. (family Dracaenaceae). Nolinofuroside D is (25S)-furost-5-ene-1,3,22,26-tetraol 1-O--D-galactopyranoside 26-O--D-glucopyranoside (I), and nolinofuroside F is (25S)-furost-5-ene-1,3,22,26-tetraol 1-O--D-fucopyranoside 26-O--D-glucopyranoside 3-O--L-rhamnopyranoside (VII). The latter was characterized as its 22-O-methyl ether (VIII). Nolinofuroside E (IV) has the structure of (25S)-furost-5-ene-1,3,22,26-tetraol 26-O--glucopyranoside 1-O-[O--L-rhamnopyranosyl-(12)--D-fucopyranoside], which followed from the structure of the fermentation product (VI). The products of the fermentation of the above-named compounds were present in the plant in only trace amounts. Only one of them — nolinospiroside D (III) — has not been described previously. This monoside of the spirostan series is (25S)-spirost-5-ene-1,3-diol 1-O--D-galactopyranoside.M. V. Frunze Simferopol' State University. Institute of Chemistry of Plant Substances, Uzbek Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 678–686, September–October, 1991.     

A solution study of complex formation between iron(III) and oxalate in dimethylsulphoxide

Summary The complex formation between iron(III) and oxalic acid (ethanedioic acid, H₂ox) has been studied by potentiometry in dimethylsulphoxide (dmso) solution. H₂ox behaves as a weak diprotic acid in such a solvent, with overall association constants: log _j1=8.551(3) and log _j2=14.242(3) at 25°C and 0.1 Mn-Bu₄NClO₄. A reliable set of overall stability constants for the iron(III)-oxalato complexes, log ₁₁=13.16(4), log ₁₂=23.66(4) and log ₁₃=30.75(4), have been obtained for the first time under identical conditions. The electrochemical behaviour of such complexes was studied in dmso at a platinum electrode. The coordination ability of oxalate towards iron(III) in dmso and water media is compared and discussed in the light of thermodynamic and structural parameters.     

Octahedral and tetrahedral configuration changes of nickel(II) chloro complexes from spectrophotometric studies in aprotic solvents

Four NiII chloro complexes were identified spectrophotometrically in aprotic media such as DMSO, DMF and propylene carbonate for the first time. An original multiwavelength numerical treatment, based on a Marquardt method, results in the determination of the individual electronic spectra of the mononuclear chloro complexes and of their stability constants, the values of which indicate the presence of rather weak complexes in DMSO and DMF, much stronger in the less solvating propylene carbonate solvent. The overall stability constants calculated for the NiII chloro complexes are: 1=52, 2=140, 3=160, 4=210 in DMSO, 1=60, 2=110, 3=900, 4=15000 in DMF, 1=1.6×109, 2=6.4×1015, 3=2.7×1021, 4= 5.1×1026 in PC.The solvent effect is discussed in terms of the quantitative results obtained from this spectrophotometric study and reveals that the stability of the complexes is an inverse function of the donor properties of the solvent. This result illustrates the general behavior of complex formation in dipolar aprotic solvents, i.e. the substitution of one solvent molecule in the inner coordination sphere by the ligand is easier if the solvation strength of the solvent is lower. The solvent effect is also described in terms of the variation of shifts of the calculated absorption maxima for the individual electronic spectra of the chloro complexes. This result is used to identify clearly at which step of coordination the octahedral configuration of the nickel ion changes to the tetrahedral configuration, by comparison with the well-known structural properties of these complexes in the solid state.     

Researches on 2, l, 3-thia- and selenadiazole

4-(,-Dicarboethoxy--acetylamino) ethyl-7-aminobenzo-2,1, 3-thiadiazole (IV) and ethylene oxide form mainly the 7-(-hydroxyethyl) amino derivative (V); the 7- di (-hydroxyethyl) amino derivative VII was isolated in low yield. Action of POCl₃ on compound VII gave the 7-di (-chloroethyl) amino derivative VIII, which was converted into 4-(-amino--carboxy)-ethyl-7 -di (-chloroethyl) aminobenzo-2, 1, 3-thiadiazole (IX). 5-(, -dicarboethoxy--acetylamino) ethyl-4-nitrobenzo-2, 1, 3-thiadiazole (XI) was converted to 5-(-carboxy--amino) ethyl-4-nitrobenzo-2, 1, 3-thiadiazole hydrochloride (XII), from which was prepared, by known routes, and in satisfactory yield, 5-(-carboxy--amino) ethyl-4-di (-chloroethyl)-aminobenzo-2, l, 3-thiadiazole hydrochloride (XVII).For Part XXXIX see [8].     

Inclusion Complexes of Cyclodextrins with Tetrakis(4-carboxyphenyl)porphyrin and Tetrakis(4-sulfonatophenyl)porphyrin in Aqueous Solutions

In neutral and alkaline solutions, tetrakis(4-carboxyphenyl)porphyrin (TCPP) and tetrakis(4-sulfonatophenyl)porphyrin (TSPP) form 1:1 and 2:1 host–guest inclusion complexes with -cyclodextrin (-CD), -cyclodextrin (-CD), and 6-deoxy-6-diethylamino--CD (DEA--CD), except for DEA--CD in alkaline solution. On the other hand, TCPP and TSPP form only 1:1 inclusion complexes with 6-deoxy-6-dihexylamino--CD (DHA--CD). The limited solubilities of DEA--CD in alkaline solution and DHA--CD are likely responsible for no observation of the 2:1 inclusion complex containing DEA--CD in alkaline solution and that containing DHA--CD. The equilibrium constants (Ks) of TCPP and TSPP for the formation of the inclusion complexes have been estimated from the absorption and/or fluorescence intensity changes in neutral and alkaline solutions. The K₂ values, which are the equilibrium constants for the formation of the 2:1 host–guest inclusion complex from the 1:1 inclusion complex, are about one tenth the corresponding K₁ values, except for the -CD–TSPP system in alkaline solution. In neutral solution, where DEA--CD and DHA--CD are in protonated forms, the electrostatic force operates between DEA--CD (DHA--CD) and TCPP (TSPP), leading to the greater K values than those in alkaline solution, where DEA--CD and DHA--CD exist as neutral species.     

Structural Studies on Host + Guest Recognition Sensory Systems

Rhodamine B-ethylenediamine--cyclodextrins (RhB--CDen) and rhodamine B--cyclodextrins (RhB--CD) can form inclusive complexes with many guest molecules, a reaction which can be used as a nucleic acid probe. In this paper, the most stable conformations of RhB--CDen and RhB--CD have been determined by fluorescence experiments and analyzed by molecular modeling simulation. The interaction between RhB--CDen and two guest molecules, 1-borneol and cyclohexanol, has also been investigated. The results showed that RhB--CDen has a stronger interaction with 1-borneol than with cyclohexanol. Borneol could push the three aromatic-rings of rhodamine B out of the CD cavity, while the cyclohexanol could not. The interactive sites of host and guest are also presented.     

Spectroscopic and thermodynamic studies on solvatochromic nickel(II) complexes

Summary The solvatochromic and thermochromic behaviour of a series of mixed Ni(II) complexes with unsubstituted and substituted -diketones and diamines in the solvents 1,2-dichloroethane (DCE), acetonitrile (An), acetone (AC),n-butanol (n-BuOH), formamide (FA), N,N-dimethylformamide (DMF), dimethylsulfoxide (DMSO) and pyridine (PY) has been studied and characterized on the basis of electronic spectra. Spectrophotometric methods have been used to evaluate equilibrium constants and their enthalpic and entropic terms for the formation of Ni(-dik)(diam)L ⁺ and Ni(-dik)(diam)L ₂ ⁺ . Increasing donor strength of the donor-solvents (L) and (or) increasing electronwithdrawing parameters of the substituents at the -diketone and the diamine ligands lead to increasing formation constants, paralleled by relative increase in the stability of the five-coordinated species Ni(-dik)(diam)L ⁺. The results are discussed in terms of the extended donor-acceptor concept.On leave of absence from the Faculty of Education, Ain Schams University, Roxy, Cairo, Egypt     

Some Pharmaceutical Properties of a New Branched Cyclodextrin, 6-O-α-(4-O- α-D-Glucuronyl)-D-glucosylβ-cyclodextrin

Some physicochemical and biological properties of a new branched cyclodextrin, 6-O--(4-O--d-glucuronyl)-d-glucosyl--cyclodextrin GUG--CyD) were investigated. Further, theinteraction of GUG--CyD with several drugs was studied by the solubility and spectroscopic methods, and compared with those of parent -CyD and 6-O--maltosyl--CyD(₂--CyD).The hemolytic activity of GUG--CyD on rabbit erythrocytes was lower than those of -CyD and ₂--CyD. GUG--CyD and ₂--CyD showed negligible cytotoxicity on Caco-2 cells up to at least 0.1 M. The inclusion ability of GUG--CyD to neutral and acidic drugs was comparable to or slightly smaller than those of -CyD and ₂--CyD, probably because of a steric hindrance of the branched sugar. On the other hand, GUG--CyD showed greater affinity for the basic drugs, compared with -CyD and ₂--CyD, owing to the electrostatic interaction of its carboxylate anion with positive charge of basic drugs. Thus GUG--CyD may be useful as a safe solubilizing agent particularly for basic drugs.     

Rotaxane Type Complexation Behavior of Cyclodextrins with Zinc (II) Tetraphenylporphyrin-Viologen Linked Compounds

The complexation behavior of zinc (II) tetraphenylporphyrin-viologen covalently linkedcompounds by a polymethylene chain (ZnPC_nV²⁺; n = 4–9) withtri-O-methyl--cyclodextrin (TM--CD) was investigated by meansof ¹H NMR and UV/Vis absorption spectrometry in acetonitrile-water (1:1, v/v).The ¹H NMR spectra indicated that ZnPC_nV²⁺ existed as a mixture ofa dimer and a monomer at high concentration (>1 × 10^-3 M). The dimerwas degraded to the monomer upon complexation with TM--CD involving theformation of 1:1 and 1:2 (ZnPC_nV²⁺: TM--CD) complexes, whichwas observed by UV/Vis spectrometry. Furthermore, ¹H NMR spectra exhibitedthat there are at least two types of structures for these complexes, one is a fastexchanging complex, and another is a slow exchanging one. A slow exchanging complexcould be assigned as a rotaxane type structure in which the methylene chain moiety ofZnPC_nV²⁺ penetrated into the cavity of TM--CD. Discrete formationconstants for these complexes were evaluated. The values were little affected by the spacermethylene chain length (n 7).     

Proanthocyanidins ofPolygonum coriarium III. Structures of proanthocyanidins T1 and T2

The roots ofPolygonum coriarum have yielded two oligomeric proanthocyanidins, T1 and T2, and their structures have been established: 3-O-galloyl-7-O-[O-(6-O-galloyl)--D-glucopyranosyl]-(–)-epigallocatechin-(4-8)-(–)-epicatechin-(4-8)-(–)-epicatechin-(4-8)-(–)-epigallocatechin 3-O-gallate (T1) and (–)-epicatechin-(4-8)-[3-O-galloyl-(–)-epigallocatechin]-(4-8)-(–)-epicatechin-(4-8)-(+)-catechin (T2).The material of this paper were presented at the IInd International Symposium on the Chemistry of Natural Compounds (SCNC, Eskisehir, Turkey, October 22–24, 1996).Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 588–593, July–August, 1977.