Usage of nonporous polymeric particles for reversed-phase high-performance liquid chromatography of oxidized and deamidated forms of recombinant human growth hormone

In this work, a C(18) reversed-phase column with nonporous polymeric 2.5- micro m particles is utilized to initially test the analysis of oxidized and deamidated human growth hormone (hGH). Phosphate buffer (pH 7.5) with 24% 1-propanol was used for elution. This quick method (analysis time is 20 min) gave a selectivity, as judged by the number of detected peaks, and resolution of hGH variants that is better than many methods in which porous silica particle columns are used. Only mixtures of oxidized and deamidated hGH are analyzed, and no characterization of the peaks is performed. The results indicate that C(18) nonporous polymeric column material is a promising alternative for the chromatographic separation of several hGH variants.     

Measurement of the sign and the magnitude of heteronuclear coupling constants from spin-state-edited J-cross-polarization NMR experiments

New spin-state-selective (S3) NMR pulse sequences exclusively applying cross-polarization schemes to achieve optimum homonuclear and heteronuclear 1H-X coherence transfer are reported for the simple and accurate measurement of the magnitude and sign of heteronuclear coupling constants for samples at natural abundance. The proposed spin-edited HCP-TOCSY experiments are based on clean heteronuclear S3 excitation, generated by simultaneous co-addition of two independent in-phase and anti-phase components created during the mixing heteronuclear J-cross-polarization (HCP) step, which is finally transferred to other protons by a conventional homonuclear TOCSY mechanism. Selective 1D and non-selective 2D approaches for the easy determination of long-range proton-carbon and proton-nitrogen coupling constants on any protonated and non-protonated heteronuclei are presented and discussed for several organic molecules.     

Synthesis and characterization of heavier dioxouranium(VI) dihalides

The synthesis and characterization of the dioxouranium(VI) dibromide and iodide hydrates, UO(2)Br(2)x3H(2)O (1), [UO(2)Br(2)(OH(2))(2)](2) (2), and UO(2)I(2)x2H(2)Ox4Et(2)O (3), are reported. Moreover, adducts of UO(2)I(2) and UO(2)Br(2) with large, bulky OP(NMe(2))(3) and OPPh(3) ligands such as UO(2)I(2)(OP(NMe(2))(3))(2) (4), UO(2)Br(2)(OP(NMe(2))(3))(2) (5), and UO(2)I(2)(OPPh(3))(2)(6) are discussed. The structures of the following compounds were determined using single-crystal X-ray diffraction techniques: (1) monoclinic, P2(1)/c, a = 9.7376(8) A, b = 6.5471(5) A, c = 12.817(1) A, beta = 94.104(1) degrees , V = 815.0(1) A(3), Z = 4; (2) monoclinic, P2(1)/c, a = 6.0568(7) A, b = 10.5117(9) A, c = 10.362(1) A, beta = 99.62(1) degrees , V = 650.5(1) A(3), Z = 2; (4) tetragonal, P4(1)2(1)2, a = 10.6519(3) A, b = 10.6519(3) A, c = 24.0758(6) A, V = 2731.7(1) A(3), Z = 4; (5) tetragonal, P4(1)2(1)2, a = 10.4645(1) A, b = 10.4645(1) A, c = 23.7805(3) A, V = 2604.10(5) A(3), Z = 4, and (6) monoclinic, P2(1)/c, a = 9.6543(1) A, b = 18.8968(3) A, c = 10.9042(2) A, beta =115.2134(5) degrees , V = 1783.01(5) A(3), Z = 2. Whereas 1 and 2 are the first UO(2)Br(2) hydrates and the last missing members of the UO(2)X(2) hydrate (X = Cl --> I) series to be structurally characterized, 4 and 6 contain room-temperature stable U(VI)-I bonds with 4 being the first structurally characterized room temperature stable U(VI)-I compound which can be conveniently prepared on a gram scale in quantitative yield. The synthesis and characterization of 5 using an analogous halogen exchange reaction to that used for the preparation of 4 is also reported.     

Vesicle adsorption and lipid bilayer formation on glass studied by atomic force microscopy

The adsorption of phosphatidylcholine (PC) vesicles (30, 50, and 100 nm nominal diameters) and of dye-labeled PC vesicles (labeled with 6% Texas Red fluorophore (TR) and encapsulated carboxy fluorescein (CF)) to glass surfaces was studied by contact mode atomic force microscopy in aqueous buffer. These studies were performed in part to unravel details of the previously observed isolated rupture of dye-labeled PC vesicles on glass (Johnson, J. M.; Ha, T.; Chu, S.; Boxer, S. G. Biophys. J. 2002, 83, 3371-3379), specifically to differentiate partial rupture, that is, pore formation and leakage of entrapped dye, from full rupture to form bilayer disks. In addition, the adhesion potential of PC vesicles on glass was calculated based upon the adhesion-driven flattening of adsorbed vesicles and a newly developed theoretical model. The vesicles were found to flatten considerably upon adsorption to glass (width-to-height ratio of approximately 5), which leads to an estimate for the adhesion potential and for the critical rupture radius of 1.5 x 10(-4) J/m2 and 250 nm, respectively. Independent of vesicle size and loading with dye molecules, the adsorption of intact vesicles was observed at all concentrations below a threshold concentration, above which the formation of smooth lipid bilayers occurred. In conjunction with previous work (Johnson, J. M.; Ha, T.; Chu, S.; Boxer, S. G. Biophys. J. 2002, 83, 3371-3379), these data show that 6% TR 20 mM CF vesicles adsorb to the surface intact but undergo partial rupture in which they exchange content with the external buffer.     

Thermal analysis of metal complexes,III

On the basis of the thermal investigation of Mpy_nX _z mixed complexes (where M=Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺; py=pyridine; or-, - and-picoline; X=Cl^–, Br^–, I^–, OCN^–, SCN^–, NO ₃ ^– , SO ₄ ^2– ; andn=2,3,4,6;z=1,2), factors influencing the stability of the metal-pyridine-N bond have been determined.On the basis of the measured magnetic susceptibilities the symmetry of the coordina tion sphere of the central atom has been established in the intermediate products formed by the thermal decomposition of cobalt(II) complexes.

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Zusammenfassung Aufgrund derivatographischer Untersuchungen von Mischkomplexen des Typs Mpy_nX_z (M=Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺; py=Pyridin,, und Piccolin; X=Cl^–, Br^–, I^–, OCN^–, SCN^–, NO ₃ ^– , SO ₄ ^2– ;n=2, 3, 4, 6;z=1, 2) wurden die die StabilitÄt der Metall-Pyridin-N Bindung beeinflussenden Faktoren geprüft. Durch Messung der magnetischen SuszeptibilitÄten wurde die Symmetrie der KoordinationssphÄre des Zentralatoms des bei der thermischen Zersetzung entstehenden Kobalt(II)-komplexes ermittelt.

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Résumé On a examiné des complexes du type Mpy _n X _z (où M=Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺; py=pyridine,-,- et-piccoline; X=Cl^–, Br^–, I^–, OCN^–, SCN^–, NO ₃ ^– , SO ₄ ^2– ;n=2, 3, 4, 6;z=1, 2) dans le but de déterminer les facteurs ayant une influence sur la stabilité de la liaison métal-pyridine-N. Par mesure des susceptibilités magnétiques, on a pu établir dans la cas des complexes du Co²⁺ la sphère de coordination de l'atome central pour les phases intermédiaires produites par décomposition thermique.

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_nz ( M=n²⁺, ²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺; py= , , ; X=Cl^–, Br^–, I^–, OCN^–, SCN^–, NO₃ ^–, SO ₄ ^2– ; n=2, 3, 4, 6; z=1, 2) , --N. , (II).

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Previous paper of the series: G. Liptay, K. Burger, E. Papp Molnár, Sz. Szebeni, F. Ruff: J. Inorg. Nucl. Chem. 31 (1969) 2359.

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We are indebted to Miss é. Szabó for technical assistance.     

Zur Ermittlung und rechnerischen Überprüfung thermodynamischer Daten aus experimentell gefundenen Werten, 10. Mitt.: Zur Frage der Parameterzahl und Fehlerverteilung bei einigen Rechenansätzen für binäre thermodynamische Systeme

Zusammenfassung Es wird eine vergleichende Untersuchung über die Anwendungsmöglichkeit zweier dreiparametriger und zweier zweiparametriger Ansätze angestellt. Die Bestimmung der Konstanten erfolgt nach der Methode der kleinsten Quadrate, die entstehenden Fehlerquadratsummen werden als Funktion der Iterationszahl dargestellt und verglichen. Ebenso wird mit den Verbesserungen _i und den mittleren Fehlern der einzelnen Parameter verfahren. Es ergibt sich, daß der Ansatz vonWilson für stark assoziierende Systeme mit nahezu horizontaler Grenztangente die kleinste Fehlerverteilung aufweist. Die beiden dreiparametrigen Ansätze vonRedlich-Kister und vonMusil-Breitenhuber zeigen sich für das Systemn-Hexan-Methylamin besser geeignet als für die Systeme Benzol-Methanol und CCl₄-Methanol. Die Problematik der Parameterzahl wird an Hand der Fehlerverteilung bei den Ansätzen vonMB undRK aufgezeigt und diskutiert.Das Programm wurde in der Programmiersprache FORTRAN erstellt und mit der UNIVAC-490-Computer-Anlage des Grazer Rechenzentrums gerechnet.

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Four thermodynamical statements are tested with regard to their applicability to binary systems, two statements having three and two only two parameters. The least square method ofGauss shows that theWilson statement has the smallest dispersion of errors for systems with nearby horizontal boundary tangent. [vv], _i and are shown as functions of the number of iterations. The problem of the parameters' number is shown and discussed by means of the dispersion of errors for theMusil-Breitenhuber (MB) andRedlich-Kister (RK)-statements.The programme is written in FORTRAN and has been used the UNIVAC-490-Computer of the Graz Computer Centre.

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Mit 5 Abbildungen

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Herrn Professor Dr.Robert Fischer zum 65. Geburtstag in Dankbarkeit und Verehrung gewidmet.

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bis 6. Mitt.:F. Gölles, Mh. Chem.92, 981 (1961);93, 191, 201 (1962);94, 1108 (1963);95, 1656 (1964);96, 1366 (1965);7. bis 9. Mitt.:F. Gölles undA. Höpfner, Mh. Chem.97, 368, 911 (1966);99, 230 (1968).     

Preparation of R- and S-mevalonolactones

(+)-Linalool has been converted into R(−)-mevalonolactone by a four-step procedure in 21 per cent overall yield. The final step introduces a new method for the fission of ---CO---CH₂---to ---CO₂H HO₂C---. (—)-Linalool similarly afforded S(+)-mevalonolactone. The absolute configuration of (+)- and (−)-linalools are established by this work as S and R respectively.     

Developing an on-line derivatization of FAs by microwave irradiation coupled to HPLC separation with UV detection

The development of analytical methods for routine simultaneous identification and quantification of carboxylic fatty acids (CFAs) are required in different fields, such as, pharmaceutical cosmetics, food products and formulations of water–microemulsion–oil systems. Determination of CFAs has been developed mainly by gas chromatography (GC). As an alternative to GC, liquid chromatography (LC) has better sensitivity and selectivity. However, most CFAs show no useful absorption in ultraviolet–violet (UV–Vis) region, one of the more used detection technique in high-performance liquid chromatography (HPLC). In order to allow the use of UV–Vis detection, the use of pre-column derivatization has been reported to increase sensitivity and selectivity. Therefore, establishment of a simpler and faster on-line method with complete separation is needed for the screening of large numbers of samples. 2,4-Dinitrophenylhydrazine (2,4-DNPH.), benzoil chloride (BC), and phenylhydrazine (PH) were used for derivatization of different FAs by microwaves radiation (MW). After the on-line derivatization, products were separated and quantified by HPLC. Reactor coil was placed inside of microwaves oven at 450 W. Parameters as flow, amount of reagents, irradiation time, and chromatographic conditions were optimized. The continuous analysis using the MW–HPLC–UV system provided high sensitivity and reduced both the amount of reagent used and the analysis times. This proposed method can be used for the routine analysis of FAs contained in water–microemulsion–oil systems, to quantify the total acid fraction in each phase.     

Formation of Zn(1-x)MnxS nanowires within mesoporous silica of different pore sizes

Arrays of highly ordered Zn(1-x)MnxS quantum wires with x ranging from 0.01 to 0.3 and with lateral dimensions of 3, 6, and 9 nm were synthesized within mesoporous SiO2 host structures of the MCM-41 and SBA-15 type. The hexagonal symmetry of these arrays (space group p6m) and the high degree of order was confirmed by X-ray diffraction and transmission electron microscopy (TEM) studies. Physisorption measurements show the progressive filling of the pores of the SiO2 host structures, while TEM and Raman studies reveal the wire-like character of the incorporated Zn(1-x)MnxS nanostructures. X-ray absorption near-edge structure, extended X-ray absorption fine structure, photoluminescence excitation (PLE), and electron paramagnetic resonance studies confirm the good crystalline quality of the incorporated Zn(1-x)MnxS guest species and, in particular, that the Mn2+ ions are randomly distributed and are situated on tetrahedrally coordinated cation sites of the Zn(1-x)MnxS wires for all x up to 0.3. The amount of Mn2+ ions loosely bound to the surface of the Zn(1-x)MnxS nanowires is less than 4% of the total Mn content even for the 3 nm nanostructures up to the highest Mn content of x = 0.3. The effects of the reduction of the lateral dimensions on electronic properties of the diluted magnetic semiconductor were studied by PLE spectroscopy. Due to the quantum confinement of the excitons in the wires an increase of the direct band gap with decreasing particle size is observed.     

The Staudinger ligation-a gift to chemical biology

Although the reaction between an azide and a phosphane to form an aza-ylide was discovered by Hermann Staudinger more than 80 years ago and has found widespread application in organic synthesis, its potential as a highly chemoselective ligation method for the preparation of bioconjugates has been recognized only recently. As the two reaction partners are bioorthogonal to almost all functionalities that exist in biological systems and react at room temperature in an aqueous environment, the Staudinger ligation has even found application in the complex environment of living cells. Herein we describe the current state of knowledge on this reaction and its application both for the preparation of bioconjugates and as a ligation method in chemical biology.