Conformational changes in the human serum albumin-indomethacin binding

The effect of a nonsteroidal anti-inflammatory drug, the indomethacin, on the conformation of human serum albumin is investigated by evaluating-helix,-structure and random coil structure contents from optical rotatory dispersion spectra. The observed structural changes may be attributed to the-helix-to--structure conversion, because the content of random coil is not largely changed. The increase in-structure is due to a loss in the degrees of freedom in albumin.     

Phase behavior and dynamic properties in mixed systems of anionic and cationic surfactants: lithium perfluorooctanesulfonate/diethanolheptadecafluoro-2-undecanolmethylammonium chloride (DEFUMAC) and lithium dodecyl sulfate/DEFUMAC aqueous mixtures

Two ternary phase diagrams of the cationic perfluorosurfactant diethanolheptadecafluoro-2-undecanolmethylammonium chloride (DEFUMAC) with an anionic perfluorosurfactant lithium perfluorooctanesulfonate (LiFOS) and an anionic hydrocarbon surfactant lithium dodecyl sulfate (LiDS) have been established at 25°C. The total surfactant concentration was less than 20wt%. In a wide mixing region of the LiFOS/DEFUMAC system, a lamellar-type phase,P , was identified by its texture under a polarization microscope and by its x-ray diffraction pattern. Dispersed fragments ofP -phase are present in the dilute solutions in which one surfactant was in excess. The anisotropy of electrical conductivity, flow birefringence, dynamic light scattering, and electric briefringence demonstrate that theP fragments are disk-like with a radius of 0.7 m. The disk-likeP particles are transformed by shear into a spherical aggregate ofL above a critical shear gradient. LiDS/DEFUMAC mixed solution forms dispersed and precipitatedL in the dominant region. Radius and micropolarity of the dispersedL aggregates are decreased as the ratio of LiDS:DEFUMAC approaches 1:1. On the basis of x-ray diffraction measurement the structure of precipitatedL -phase seems to consist of monolayers.     

Molecular motions in poly(diethyl siloxane) studied by solid-state29Si NMR

Molecular motions in poly(diethyl siloxane) were studied by solid-state²⁹Si-NMR in the temperature range 180–350 K. In this temperature range two solid phases ₁ and ₂, a mesophase _m, and an amorphous isotropic phase exist. The nature of the chain mobility in the different phases was deduced from the resulting changes in the NMR line-shape governed by anisotropic chemical shift. In the intermediate solid phase ₂ its anisotropy is reduced by 25% compared with the low temperature phase ₁ due to the onset of oscillations around the chain axis and conformational transitions. In the mesophase _m the polymer chain rotates about its long axis yielding an axially symmetric chemical shift tensor opposite in sign to that in the ₁, ₂ phases. The broad transition of the mesophase into the isotropic phase is accompanied by an increase in a narrow Lorentzian line arising from the amorphous phase. The results are compared with previous¹H NMR, Raman-spectroscopy and x-ray measurements.After completion of this work we learnt that PDES has recently also been studied through¹³C-MAS and²⁹Si-NMR by Möller et al. [13].     

Shear-induced deformation of polystyrene coils in dilute solution from small angle neutron scattering 2. Variation of shear gradient,molecular mass and solvent viscosity

The technique of small angle neutron scattering (SANS) has been used to study the conformation of polystyrene chains in dilute solution under a constant shear gradient. The experiments reveal a distinct anisotropy of the molecular dimensions with regard to the directions parallel and perpendicular to the flow direction on the 2D-multidetector. The deformation ratio of the single polymer chain (R ²/R _iso ² )–1 as a function of the reduced shear gradient=([] · · M _w G)/RT shows a transition from the ideal ²-behaviour for dynamic infinitely flexible coils found at small gradients, to a behaviour with smaller increase at larger. These results are qualitatively consistent with the theory of Cerf for a polymer with finite internal viscosity in a shear gradient. At low(<1), a better agreement with the model of a free-draining coil (Rouse behaviour) than with the Zimm model is observed.     

Steroid compounds from the starfish Lysastrosoma anthosticta collected in the Sea of Japan

Six polyhydroxylated steroids and their derivatives were isolated from the starfish Lysastrosoma anthosticta collected in the Posyet Bay, Sea of Japan. These include a new glycoside of the steroid polyol, lysastroside A (1), which was identified as (25S)-26-O--d-xylopyranosyl-5-cholestane-3,6,8,15,16,26-hexaol, and the previously known pycnopodioside C monoglycoside (2), marthasterone sulfate (3), (25S)-5-cholestane-3,6,8,15,16,26-hexaol (4), (25S)-5-cholestane-3,6,7,8,15,16,26-heptaol (5), and (25S)-5-cholestane-3,6,7,8,15,16,26-heptaol (6). The compounds were tested for the haemolytic activity and the action on the embryogenesis of the sea urchin Strongylocentrotus intermedius.     

Phase diagram of the system dihexadecylphosphatidylcholine/dihexadecyl-phosphatidic acid/water/NaOH at pH=14

Differential-scanning-calorimetry, freeze-fracture electron microscopy, and³¹P-NMR spectroscopy were used to study the lyotropic and thermotropic properties of the system dihexadecylphosphatidylcholine/dihexadecylphosphatidic acid/water/ NaOH in dispersion with excess water at pH=14. The phase diagram showed that both phospholipids are demixed nearly completely in the gel phase. The coexistence of theP and theB -phase in the mixtures was pointed out in the freeze-fracture electron micrographs by the ripple structure (P -phase) and by the lamellar structure (B -phase).     

Triterpene Glycosides of Tragacantha Stipulosa and Their Genins. Structures of Askendosides G and D and Cycloglobiceposide B from One- and Two-Dimensional 1H and 13C NMR Spectroscopy

Roots of Tragacantha stipulosa Boriss yielded three triterpene glycosides of the cycloartane series: askendoside G (1), askendoside D (2), and cycloglobiceposide B (3). Glycoside 1 is 3-O--L-arabinopyranosyl-(12)--D-xylopyranoside; 16-O--D-glucopyranoside-24R-cycloartan-3,6,16,24,25-pentaol; 2 - 3-O--L-arabinopyranosyl-(12)--D-xylopyranoside; 6-O--D-xylopyranoside-20R,24S-epoxycycloartan-3,6,16,25-tetraol; 3 - 3-O--D-xylopyranoside; 16-O--D-glucopyranoside; 25-O--D-glucopyranoside-24R-cycloartan-3,6,16,24,25-pentaol.     

Secondary metabolites of Astragalus danicus Retz. and A. inopinatus Boriss.

The chemical composition of the above-ground parts of Astragalus danicus and A. inopinatus collected in the Baikal region (Eastern Siberia) was studied for the first time. From A. danicus, pentacyclic triterpene saponins were isolated and identified, viz., 3-O-(-glucuronopyranosyl)-3,22,24-trihydroxyolean-12-ene, 3-O-[O-(-d-xylopyranosyl)-(12)-(-glucuronopyranosyl)]-3,22,24-trihydroxyolean-12-ene, 3-O-[O-(-d-glucopyranosyl)-(12)-(-glucuronopyranosyl)]-3,22,24-trihydroxyolean-12-ene, 3-O-[O-(-l-rhamnopyranosyl)-(12)-O-(-d-xylopyranosyl)-(12)-(-glucuronopyranosyl)]-3,22,24-trihydroxyolean-12-ene, 3-O-[O-(-l-rhamnopyranosyl)-(12)-O-(-d-glucopyranosyl)-(12)-(-glucuronopyranosyl)]-3,22,24-trihydroxyolean-12-ene, 3-O-methyl-d-chiro-inositol, and linolenic acid. In A. inopinatus, the same saponins were identified as well as tricosan-1-ol and tetracosan-1-ol, 5,7,4"-trihydroxyflavon (apigenin), and a tetracyclic triterpenoid, 20(R),24(S)-epoxycyclolanost-9(11)-ene-3,6,16,25-tetrol (cycloastragenol). All reported compounds from the both genus of Astragalus were isolated for the first time. Methanolic extracts of A. danicusand A. inopinatus exhibited low inhibitory activity with respect to the growth of HeLa cells. The chloroform fraction of A. danicus showed a strong antimicrobial activity against Staphylococcus aureus and a strong cytotoxic activity against HeLa cells.     

Steroid compounds from the Pacific starfishesLuidia quinaria andDistolasterias elegans

One new and four previously known steroid compounds were identified from the Pacific starfishesLuidia quinaria andDistolasterias elegans. The structure of the new steroid was established from spectral data and chemical correlations with other steroids such as 5-cholestane-3,5,6,15,16,26-hexaol 3-sulfate (1). The previously known compounds were identified as 5-cholestane-3,5,6,15,26-pentaol 15-sulfate (2) fromLuidia quinaria and sodium (24S)-O-(-d-giucopyranosyll-5-cholestane-3,6,8,15,24-pentaol 6-sulfate (3), sodium (24S)-5-cholestane-3,6,8,15,24-pentaol 24-sulfate (4), and sodium tornasterol A sulfate (5).Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 473–476, February, 1996.     

Steroid glycosides from the starfishSolaster dawsoni (Verrill)

Two novel glycosides from the starfishSolaster dawsoni (Verrill) have been isolated and characterized: 24-O-(-D-xylopyranosyl)-5-cholestane-3,6,15,24,26-pentaol (solasteroside S₁) and (24R)-29-O-[-D-galactofuranosyl-(16)--D-galactofuranosyl]-24-ethyl-5-cholestane-3, 6,8,15,16,29-hexaol (solasteroside S₂).Translated fromIzvestiya Akademu Nauk. Seriya Khimicheskaya, No. 5, pp. 980–982, May, 1993.     

Triterpene glycosides from Pulsatilla chinensis

Four triterpene glycosides were isolated from the roots of Pulsatilla chinensis (Bunge) Regel (Ranunculaceae). Two new glycosides, chinensiosides A (1a) and B (2), were identified as 3-O-[-L-rhamnopyranosyl-(12)--L-arabinopyranosyl]-28-O-[-L-rhamnopyranosyl-(14)--D-glucopyranosyl-(16)--D-glucopyranosyl]-3,23-dihydroxylup-20(29)-en-28-oic acid and 3-O-{-L-rhamnopyranosyl-(12)-[-D-glucopyranosyl-(14)]--L-arabinopyranosyl}-28-O-[-L-rhamnopyranosyl-(14)--D-glucopyranosyl-(16)--D-glucopyranosyl]-3,23-dihydroxylup-20(29)-en-28-oic acid. The other two glycosides were identified as previously known hederasaponin C (3) from Hedera helix and glycoside III (4) from Pulsatilla cernua.     

Unusual oxidation reactions of 7α-methyl- and 7α-phenylcholest-5-ene-3β,7β-diol

Summary Ozonation of 7-methyl (or 7-phenyl) cholest-5-ene-3,7-diol 3-TBDMS ether afforded the corresponding 5,6-epoxy derivatives. The same product was formed byMCPBA oxidation. The reaction of 7-phenylcholest-5-ene-3,7-diol with CrO₃ yielded 3,7-dioxo-6,7-seco-7-phenylcholest-4-ene-5-carboxaldehyde. An analogous B-seco aldehyde was obtained from 7-methylcholest-5-ene-3,7-diol in addition to 7-methylcholesta-4,6-dien-3-one.Jones oxidation of 7-phenylcholest-5-ene-3,7-diol or B-seco-aldehyde gave 3,7-dioxo-6,7-seco-7-phenylcholest-4-en-6-oic acid isolated as its methyl ester upon treatment with diazomethane.

---

Ungewöhnliche Oxidation von 7-Methyl- und 7-Phenylcholest-3-en-3,7-diol

Zusammenfassung Ozonolyse von 7-Methyl- bzw. 7-Phenyl-cholest-3-en-3,7-diol-3-TBDMS-ether ergab die entsprechenden 5,6-Epoxy-Derivate.MCPBA-Oxidation führte zum gleichen Ergebnis. Bei der Reaktion von 7-Phenyl-cholest-5-en-3,7-diol mit CrO₃ wurde 3,7-Dioxo-6,7-seco-7-phenyl-cholest-4-en-5-carbaldehyd gebildet. Einen analogen B-seco-Aldehyd erhält man neben 7-Methyl-cholesta-4,6-dien-3-on auch aus 7-Methyl-cholest-5-en-3,7-diol. DurchJones-Oxidation von 7-Phenyl-cholest-5-en-3,7-diol oder B-seco-Aldehyd erhält man 3,7-Dioxo-6,7-seco-7-phenylcholest-4-en-6-carbonsäure, die nach Behandlung mit Diazomethan als ihr Methylester isoliert wurde.

     

Effect of thick fixed-charge layers on electrostatic interaction — a theoretical approach

The electrostatic interaction pressure of charged surface layers is considered qualitatively and quantitatively. In the case of mutual penetration of the surface layers in addition to Maxwell stress and osmotic resp. hydrostatic pressure an isotropic stress on the fixed charges carrying molecules of the surface layers has to be taken into account. The derivation of the pressure-distance equations is given starting from both thermodynamic/electrostatic and hydrostatic/electrostatic principles. A possible biological significance of the additional stress is discussed emphasizing its role in modifying the structure of surface layer molecules.List of symbols e ₀ elementary charge - k Boltzmann constant - n _i concentration of theith ionic species in the bulk solution - P hydrostatic pressure - P hydrostatic pressure in the bulk volume (× ) - P ^h integration constant, independent on ×:P ^h =P(h) - T absolute temperature - Z _i electrovalence of theith ionic species - thickness of the surface layer - , ₀ relative and absolute permittivities - II(×) osmotic pressure at position × - II osmotic pressure in the bulk solution (× ) - osmotic pressure in the symmetry plane of interacting identical surface layers (electric field strength equals zero) - integration constant, independent on ×: - _e ^h electrostatic component of the disjoining pressure _e ^h = _e (h) - (×) mobile charge density profile (cations and anions of the electrolyte) - (×) fixed charge density profile - ^t(x) total charge density profile ( ^t = +) - ¹(x) fixed charge density profile of one of the two surface layers ( ¹(×) 0 for 0×) - (×) electric potential profile     

Polyhydroxysteroids from the Far-Eastern starfishCtenodiscus crispatus

Four new polyhydroxysteroids, 5-cholesta-3,5,6,15,16,25,26-heptaol, 24-ethyl-5-cholesta-3,5,6,15,28,29-heptaol-29-sulfate, (22E)-24-methyl-5-cholest-22-ene-3,5,6,15,25,26-hexaol-26-sulfate, 24-propyl-5-cholesta-3,5,6,8,15,28,29-heptaol, and the known 5-cholesta-3,5,6,15,16,26-hexaol, have been isolated from the starfishCtenodiscus crispatus.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1821–1825, October, 1994.     

Steroidal polyols from Far-Eastern starfishes Henricia sanguinolenta and H. leviuscula leviuscula

Two new compounds were isolated from two Far-Eastern starfish species, Henricia sanguinolenta and H. leviuscula leviuscula, collected in the Sea of Okhotsk, viz., the glycoside sanguinoside C, (20R,22E,24R,25S)-3-O-(2,3,4-tri-O-methyl--xylopyranosyl)-24-methyl-5-cholest-22-ene-3,4,6,8,15,26-hexol, and a steroidal ketone, (20R,24S)-3,6,24-trihydroxy-5-cholestan-15-one. They exhibit moderate cytostatic activity with respect to the eggs of sea urchin Strongylocentrotus intermedius.     

Complex polarizability as used to analyze dielectric relaxation measurements

The effect of representing dielectric properties in terms of the complex polarizability ^c = – i is examined. Loss curves ( and tan ) are shifted towards higher frequencies, revealing the existence of new relaxations and allowing the clarifications of ones already known. We have calculated the shift ratios (at maximum or tan )/ (at maximum or tan ) from the more conventional empirical equations representing the dielectric behavior. Some examples are given.     

Structure of casein micelles I. Small angle neutron scattering and light scattering fromβ- andχ-casein

Casein is the main protein component of milk and is of remarkable colloidal stability. Under the influence of milk clotting enzymes casein shows the striking behaviour of coagulation. This clotting process has already been studied by other groups, neglecting the fact that casein is not a homogeneous protein. The purpose of the present study is focused, in this first stage, on the determination of the structure of the various casein components. In cooperation with other laboratories we have been able to obtain the well separated individual proteins. Studies have been performed so far with- and-casein. For detailed structural information we carried out small angle neutron scattering and combined static and dynamic light scattering measurements and determined the molecular weight,M _w, the radius of gyration, S ² the hydrodynamic radius,R _H, the-value and the particle scattering factor, P_z(q). The two caseins show a strikingly different behaviour. For the-casein we found a star-like structure, i. e. an aggregation pattern that is expected for a common micelle. The micelle consists of about 38 monomer chains. The aggregates of-casein appear to be composed of star-like submicelles, where each submicelle contains nine-casein chains and the total degree of aggregation is about 140.     

The effect of segment length and concentration on dielectric properties of polypropyleneoxide-based polyurethanes

Three series of segmented polyurethanes based on MDI, variable chain extender, and polypropylene oxide of MW=1000, 2000, and 3000 were synthesized and their dielectric behavior examined.Dielectric relaxations in the segmented polyurethanes were investigated between –150°C and +150°C in the 100 Hz to 10 kHz range. In general, three transitions, designated as, , and were observed, and ascribed in accordance with calorimetric relaxations to glass transitions of the hard and soft segments, and Shatzki-type motions, respectively. The effect of structure variables such as soft segment size, type of chain extender (ethylene glycol, butane diol, and hexane diol) and soft segment concentration, as well as the effect of interaction of the phases on dielectric properties was discussed. It was found that a certain degree of phase mixing exists in all series, detected by the variation of theT _g of the soft segment with soft segment concentration, contrary to DSC results, which was ascribed to thermal treatment prior to the dielectric measurements. It appears that interfacial polarization becomes important only above the transition temperature.     

Reatarding effect of nitrogen ylide for the polymerization of N-vinyl pyrrolidone

-Picolinium-p-chlorophenacylide (-PCFY) acts as a retarder for polymerization of N-vinyl pyrrolidone. The polymerization runs were carried out at 60°C using benzene as an inert solvent. The kinetic equation for the present system may be written asR _p [-PCPY]^–1.0 [AIBN]^0.66[N-VP]^1.0. The value of overall energy of activation for polymerization in presence and absence of-PCPY was computed as 44.0 and 42.3 kJ mol^–1, respectively. The inverse relationship ofR _p and¯M _v with-PCPY suggests that-PCPY acts as a polymerization retarder. The retarding effect is also evidenced by higher initiator exponent value and higher value of energy of activation in presence of ylide. A mechanism is also proposed in which polymer propagating chain combines with one ylide component to give resonance stabilized radical.     

New cardenolides from the leaves ofGomphocarpus fruticosus

Two new glycosides, gomphotin (1) and gomphotoxin (13), and also the known gomphoside (9) have been isolated from the leaves ofGomophocarpus fruticosus. Compounds (1) and (9) contain a 4,6-dideoxyhexosulose residue as the sugar component, and (13) a 6-deoxyhexosulose, which are attached to glycolic OH groups of the aglycons by 3-O-1,2-O-2 (9, 13) and 3-O-1,4-O-2 (1) acetal-ketal bonds. The structures of the new compounds are represented by the names (3-O-1,4-O-2)-(2,3-dihydroxy-4, 6dideoxyhexulosido)-14-hydroxy-5-card-20(22)-enolide* (1) and (3-O-1,2-O-2)-(2,3,4-trihydroxy-6-deoxyhexulosido)-14-hydroxy-5-card-20(22)-enolide* (13).State Scientific Center for Drugs of the Ministry of Health and the National Academy of Sciences of the Ukraine, Kharkov, fax 441118. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 824–832, November–December, 1995. Original article submitted May 22, 1995.