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  • 1995-1999  (58)
  • 1970-1974  (24)
  • Inorganic Chemistry  (71)
  • Biochemistry and Biotechnology  (11)
  • 1
    Electronic Resource
    Electronic Resource
    [Gd4(C2)](Cl, I)6, an Interstitially Stabilized Heteroleptic Gadolinium SesquihalideDedicated to Professor John D. Corbett on the Occasion of his 70th Birthday (1996)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 622 (1996), S. 494-500 
    Details
    ISSN: 0044-2313
    Keywords: Gadolinium sesquihalide ; interstitial carbon units ; crystal structure ; electronic structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: [Gd4(C2)](Cl, I)6, ein interstitiell stabilisiertes, heteroleptisches Gadoliniumsesquihalogenid[Gd4(C2)](Cl, I)6 erhält man aus CsI, Gd, GdCl3 und C2I4 in verschweißten Niob-Ampullen bei 1000/800°C in Form von schwarzen, glänzenden Nadeln. Die Kristallstruktur (tetragonal; P4/mbm; Z = 2; a = 1347,5(1); c = 1212,5(1) pm) ist ähnlich wie jene von Na[Mo4]O6 bzw. [Sc4B]Cl6. Trans-kantenverknüpfte [Gd6]-Oktaeder verlaufen parallel [001]. Sie enthalten interstitielle C2-Einheiten, Jedes dritte Oktaeder enthält fehlgeordnete C2-Einheiten, senkrecht zu jenen in den benachbarten [Gd6(C2)]-Oktaedern. Diese sind daher entlang der (pseudo)-C4-Achse gestaucht. Rechnungen zur elektronischen Struktur zeigen, daß insgesamt 13 Elektronen zur Auffüllung aller Metall-Metall-bindenden Zustände für eine „leere“ [Gd4]Cl6-Struktur nötig wären. Die Einlagerung der C2-Dimeren verändert die Bindungsverhältnisse in [Gd4(C2)]X6 (X = Cl, I) erheblich. Die formale Ladung von -6 der C2-Einheit wird durch das Aufsplitten der πg-Zustände reduziert, Gd—Gd und Gd—C-bindende Zustände werden besetzt und bindende dx2-y2-Orbitale kombinieren zu den am niedrigsten liegenden nicht besetzten Zuständen.
    Notes: [Gd4(C2)](Cl, I)6 is obtained from CsI, Gd, GdCl3 and C2I4 in sealed niobium containers at 1000/800°C as black, shiny needles. The crystal structure (tetragonal, P4/mbm, Z = 2, a = 1347.5(1), c = 1212.5(1) pm) is similar to that of Na[Mo4]O6 and [Sc4B]Cl6. It may be regarded as being built from octahedra sharing common trans edges running in the [001] direction. The octahedra contain C2 units as interstitials. Every third octahedron contains a disordered C2 unit perpendicular to those in the two neighboring [Gd6(C2)] octahedra and is therefore compressed in the direction of the (pseudo) C4 axis. Calculations of the electronic structure of an “empty” [Gd4]Cl6 structure reveals a total of 13 electrons necessary to occupy all metal-metal bonding states. The incorporation of a carbon dimer substantially alters the bonding conditions for [Gd4(C2)]X6 (X = Cl, I). The formal charge of -6 of the C2 unit is significantly reduced as πg states split up, Gd—Gd and Gd—C bonding states are occupied and bonding dx2—y2 orbitals combine to form the lowest unoccupied energy states.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19966220318
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  • 2
    Electronic Resource
    Electronic Resource
    A peptide isolated by phage display binds to ICAM-1 and inhibits binding to LFA-1 (1996)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 26 (1996), S. 262-270 
    Details
    ISSN: 0887-3585
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A mixed phage library containing random peptides from four to eight residues in length flanked by cysteine residues was screened using a recombinant soluble, form of human ICAM-1, which included residues 1-453, (ICAM-11-453). Phage bound to immobilized ICAM-11-453 were eluted by three methods: (1) soluble ICAM-11-453, (2) neutralizing murine monoclonal antibody, (anti-ICAM-1, M174F5B7), (3) acidic conditions. After three rounds of binding and elution, a single, unique ICAM-1 binding phage bearing the peptide EWCEYLGGYLRYCA was isolated; the identical phage was selected with each method of elution. Attempts to isolate phage from non-constrained (i.e., not containing cysteines) libraries did not yield a phage that bound to ICAM-1. Phage displaying EWCEYLGGYLRCYA bound to immobilized ICAM-11-453 and to ICAM-11-185, a recombinant ICAM-1, which contains only the two amino-terminal immunoglobulin domains residing within residues 1-185. This is the region of the ICAM-1 that is bound by LFA-1. The phage did not bind to proteins other than ICAM-1. The phage bound to two ICAM-1 mutants, which contained amino acid substitutions that dramatically decreased or eliminated the binding to LFA-1. Studies were also performed with the corresponding synthetic peptide. The linear form of the synthetic EWCEYLGGYLRCYA peptide was found to inhibit LFA-1 binding to immobilized ICAM-11-453 in a protein-protein binding assay. By contrast, the disulfide, cyclized, form of the peptide was inactive. The EWCEYL portion of the sequence is homologous to the EWPEYL sequence found within rhinovirus coat protein 14, a nonintegrin protein that binds to ICAM-1. Taken together, the results suggests that the EWCEYLGGYLRCYA sequence is capable to binding to immobilized ICAM-1. Phage display appears to represent a new approach for the identification of peptides that interfere with ICAM-1 binding to β2 integrins. © 1996 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Directed evolution of an esterase for the stereoselective resolution of a key intermediate in the synthesis of epothilones (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 58 (1998), S. 554-559 
    Details
    ISSN: 0006-3592
    Keywords: directed evolution ; esterase ; epothilon ; Pseudomonas fluorescens ; stereoselectivity ; mutator strain ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The directed evolution of an esterase from Pseudomonas fluorescens using the mutator strain Epicurian coli XL1-Red was investigated. Mutants were assayed for their ability to hydrolyze a sterically hindered 3-hydroxy ester, which can serve as a building block in the synthesis of epothilones. Screening was performed by plating esterase producing colonies derived from mutation cycles onto minimal media agar plates containing indicator substances (neutral red and crystal violet). Esterase-catalyzed hydrolysis of the 3-hydroxy ester (ethyl or glycerol ester) was detected by the formation of a red color due to a pH decrease caused by the released acid. Esterases isolated from positive clones were used in preparative biotransformations of the ethyl ester. One variant containing two mutations (A209D and L181V) stereoselectively hydrolyzed the ethyl ester resulting in 25% ee for the remaining ester. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 58: 554-559, 1998.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Modeling of anaerobic formate kinetics in mixed biofilm culture using dynamic membrane mass spectrometric measurement (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 45 (1995), S. 219-228 
    Details
    ISSN: 0006-3592
    Keywords: formate conversion ; mass spectrometer ; anaerobic conversion ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The dynamics of the anaerobic conversion of formate in a microbial mixed culture taken from an anaerobic fluidized bed reactor was studied using a new stirred micro reactor equipped with a membrane mass spectrometer. The microreactor with a toroidally shaped bottom and pitched blade turbine and a cylindrical flow guide was thermostated and additionally equipped with a pH electrode and pH control. During fed-batch experiments using formate, the dissolved gases (methane, hydrogen, and carbon dioxide), as well as the acid consumption rates for pH control were monitored continuously. Initially and at the end of each experiment, organic acids were analyzed using ion chromatography (IC). It was found that about 50% of the formate was converted to methane via hydrogen and carbon dioxide, 40% gave methane either directly or via acetate. This was calculated from experiments using H13CO3- pulses and measurement of 12CH4 and 13CH4 production rates. About 10% of the formate was converted to lactate, acetate, and propionate, thereby increasing the measured CO2/CH4 production ratio. The nondissociated formic acid was shown to be rate determining. From the relatively high Ks value of 2.5 mmol m-3, it was concluded that formate cannot play an important role in electron transfer. During dynamic feeding of formate, hydrogen concentration always increased to a maximum before decreasing again. This peak was found to be very discriminative during modeling. From the various models set up, only those with two-stage degradation and double Monod kinetics, both for CO2 and hydrogen, were able to describe the experimental data adequately. Additional discrimination was possible with the IC measurement of organic acids. © 1995 John Wiley & Sons, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260450306
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  • 5
    Electronic Resource
    Electronic Resource
    Approaches for increasing the solution stability of proteins (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 48 (1995), S. 506-512 
    Details
    ISSN: 0006-3592
    Keywords: protein stabilization ; urokinase ; denaturation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Stabilization of proteins through proper formulation is an important challenge for the pharmaceutical industry. Two approaches for stabilization of proteins in solution are discussed. First, work describing the effect of additives on the thermally induced denaturation and aggregation of low molecular weight urokinase is presented. The effects of these additives can be explained by preferential exclusion of the solute from the protein, leading to increased thermal stability with respect to denaturation. Diminished denaturation leads to reduced levels of aggregation. The second approach involves stoichiometric replacement of polar counter ions (e.g., chloride, acetate, etc.) with anionic detergents, in a process termed hydrophobic ion pairing (HIP). The HIP complexes of proteins have increased solubility in organic solvents. In these organic solvents, where the water content is limited, the thermal denautration temperatures greatly exceed those observed in aqueous solution. In addition, it is possible to use HIP to selectively precipitate basic proteins from formulations that contain large amounts of stabilizers, such as human serum albumin (HSA), with a selectivity greater than 2000-fold. This has been demonstrated for various mixtures of HSA and interleukin-4. © 1995 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260480513
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  • 6
    Electronic Resource
    Electronic Resource
    Dynamic determination of anaerobic acetate kinetics using membrane mass spectrometry (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 57 (1998), S. 127-135 
    Details
    ISSN: 0006-3592
    Keywords: membrane mass spectrometer ; kinetic measurements ; anaerobic biofilm ; acetate ; inhibition ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A small, stirred, 14.4-mL tank reactor was designed to serve as a measurement cell for short-term investigation of microbial kinetics. A mass spectrometer membrane probe allowed the measurement of the dissolved gases of hydrogen, methane, oxygen, and carbon dioxide. pH was measured by an electrode and controlled by addition of acid or alkali. The highly sensitive measurement of gases with low solubility allowed rapid measurements at very low conversion. In kinetic experiments, a stepwise increase of substrate concentration (method A) and continuous feed of substrate (method B) were used, allowing quick estimation of substrate kinetics. Acetate conversion in mixed culture biofilms from a fluidized bed reactor was investigated. Substrate inhibition was found to be negligible in the concentration range studied. Experiments at various pH values showed that the undissociated acid form was the kinetic determinant. Kinetic parameters for Haldane kinetics of protons were KSH = 1.3 × 10-5 mol m-3 and KIH = 8.1 × 10-3 mol m-3. With free acid (HAc) as the rate determining species, the kinetic parameters for method A were KSHAc = 0.005 mol m-3 and KIHAc = 100 mol m-3 and for method B were KSHAc = 0.2 mol m-3 and KIHAc = 50 mol m-3. The maximum biomass activity occurred at around pH 6.5. Acetate was exclusively converted to methane and CO2 at pH 〉 6. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 57: 127-135, 1998.
    Additional Material: 6 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Analysis and simulation of complex interactions during dynamic microfiltration of Escherichia coli suspensions (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 59 (1998), S. 189-202 
    Details
    ISSN: 0006-3592
    Keywords: artificial neural network (ANN) ; microfiltration ; cell harvesting ; membrane fouling ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Microfiltration is an important unit operation in downstream processing. However, due to the influence of membrane fouling, prediction of the filtration performance for biological suspensions is difficult. This paper describes a modeling approach that allows a comprehensive description of filtration performance. On the basis of experimental data and linguistic information, a specific artificial neural network was developed that predicts the process behavior within a certain range of parameters. This approach allows us to analyze influences of fermentation on filtration. By using extensive simulations, the interactions of 17 parameters were examined and the fouling causes determined. The model was developed for cell harvesting of Escherichia coli through a shear-enhanced module. The method can be applied to any cross-flow filtration process. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 59:189-202, 1998.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Notiz zum Magnetischen Verhalten von Li3CrO4 (1974)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 408 (1974), S. 15-20 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Notice on the Magnetic Behaviour of Li3CrO4Li3CrO4, a smaragd green powder, is due to powder photographs (Guinier-Simon-technique) isotypic with orthorhombic HT—Li3PO4, a = 6.309, b = 10.851, c = 4.952 Å, Z = 4. Between 298 and 10K the Curie-Weiss-Law is obeyed with μ=1.60 B.M. and Θ=+10 K. Below 5 K ferromagnetism is observed. ESR measurements at 4.2 K and more pronounced at 1.8 K show anisotropy of the ligand field.
    Notes: Li3CrO4, ein smaragdgrünes Pulver, ist nach Guinier-Simon-Aufnahmen isotyp mit HT-Li3PO4, a = 6,309 Å, b = 10,851 Å, c = 4,952 Å, Z = 4. Zwischen 298 und 10 K wird das Curie-Weisssche Gesetz mit μ=1,60 B.M., Θ=+10K befolgt. Unterhalb von 5 K tritt überraschend Ferromagnetismus auf. ESR-Messungen bei 4,2 K und ausgeprägter bei 1,8 K zeigen eine Anisotropie des Ligandenfeldes.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19744080104
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  • 9
    Electronic Resource
    Electronic Resource
    Zur Kenntnis von Dinitrito-kobalt(III)-Komplexen. I Darstellung und Absorptions-Spektren der Dinitrito-di(äthylendiamin)-kobalt(III)-perchlorate (1974)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 408 (1974), S. 275-282 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On Dinitrito Cobalt(III) Complexes. I. Preparation and Absorption Spectra of Di(ethylenediamine) Cobalt(III) PerchloratesCis and trans dinitrito diethylenediamine cobalt perchlorates could be prepared starting with carbonato and trans dichloro ethylenediamine cobalt perchlorate. Spectroscopic data are reported and compared with those of the corresponding dinitro complexes.
    Notes: Ausgehend von Carbonato- und trans-Dichloro-diäthylendiaminkobalt(III)-perchlorat konnten cis- und trans-Dinitrito-diäthylendiamin-kobalt(III)-perchlorate dargestellt werden. Ihre Spektren im sichtbaren Gebiet und UV werden mitgeteilt und mit den Spektren der entsprechenden Dinitrokomplexe verglichen.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19744080308
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  • 10
    Electronic Resource
    Electronic Resource
    Zur Kenntnis von Dinitrito-kobalt(III)-Komplexen. II Kinetik der Isomerisierung und der Umsetzung von cis- und trans-Dinitrito-di(äthylendiamin)-kobalt(III)-perchloraten mit Stickstoffwasserstoffsäure (1974)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 408 (1974), S. 283-292 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On Dinitrito Cobalt(III) Complexes. II. Kinetics of Isomerisation and Reaction of Cis and Trans Dinitrito Di(ethylenediamine) Cobalt(III) Perchlorates with Hydrazoic AcidAfter a reinvestigation of the kinetic data of the nitrito-nitro isomerisation of cis and trans dinitrito-di(ethylenediamine) cobaltic perchlorate, the kinetics of the reactions between both coordination compounds and hydrazoic acid, to yield the diaquo compounds, nitrogen and dinitrogen oxide, has been studied by gasvolumetric measurements in the temperature range from 1 to 15°C. In azide buffer solutions both reactions proceed independently of pH, in two stages bimolecular with regard to the complex ion and hydrazoicacid. In both cases the first stage velocity constant is five times greater than the second constant. The cis-compounds react approximately three times faster than the trans-compounds. Possible reasons for the observed facts are discussed.
    Notes: Nach nochmaliger Ermittlung der kinetischen Daten der Nitritonitro-Isomerisierung von cis- bzw. trans-Dinitrito-di(äthylendiamin)-kobalt(III)-perchlorat wurde die Kinetik der Umsetzung der beiden Komplexverbindungen mit Stickstoffwasserstoffsäure zu den Diaquo-di(äthylendiamin)-Komplexen, Stickstoff und Distickstoffmonooxid gasvolumetrisch im Temperaturbereich von 1—15°C untersucht. In Azidpufferlösungen verlaufen die Reaktionen unabhängig vom pH in zwei Stufen bimolekular in bezug auf das jeweils vorliegende Komplexion und Stickstoffwasserstoffsäure, wobei die erste Geschwindigkeitskonstante etwa fünfmal größer ist als die zweite. Die cis-Verbindungen reagieren in beiden Stufen etwa dreimal rascher als die trans-Komplexe. Mögliche Gründe für diese Beobachtungen werden diskutiert.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19744080309
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