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  • Biochemistry and Biotechnology  (10)
  • Molecular Sequence Data  (5)
  • Male
  • ddc:330
  • 1995-1999  (16)
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 58 (1998), S. 554-559 
    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.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 45 (1995), S. 219-228 
    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.
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  • 3
    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.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 57 (1998), S. 127-135 
    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.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 59 (1998), S. 189-202 
    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.
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  • 6
    ISSN: 0173-0835
    Keywords: Polymerase chain reaction ; Fingerprinting ; DNA ; Fungi ; Minisatellites ; Simple repetitive sequences ; Cryptococcus neoformans ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Minisatellites and simple repetitive DNA sequence motifs are used as conventional oligonucleotide probes in DNA-hybridization-based fingerprinting. The same oligonucleotides can be used as single primers in the polymerase chain reaction (PCR) to generate individual PCR fingerprints. In this study, the simple repetitive sequences, (CA)8, (CT)8, (CAC)5, (GTG)5, (GACA)4 and (GATA)4, and a minisatellite core sequence derived from the wild-type phage M13 (5′ GAGGGTGGCGGTTCT 3′) were used as specific, single primers to amplify hypervariable repetitive DNA sequences during PCR analysis. The potential applications of this technique are demonstrated with clinical isolates of the human pathogenic yeest, Cryptococcus neoformans. PCR fingerprint patterns have remained stable after long-term in vitro passage (〉2½ years to date). Hybridization of the primers to blots of electrophoretically separated chromosomes demonstrated that the target sequences recognized by most of the primers are dispersed through the entire yeast genome. Sequence analysis of the cloned bands obtained by PCR fingerprinting indicated that if the same or extremely similar, inversely oriented tandem repeats are located close to each other, when only one repeat-specific primer is used in the PCR, the region between these repeats is amplified. PCR fingerprinting has a wide range of current and potential applications to fungi, such as clarifying taxonomic questions, facilitating epidemiological studies and improving the diagnosis of mycotic diseases.
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  • 7
    ISSN: 0173-0835
    Keywords: Polymerase chain reaction ; Fingerprinting ; Pathogenic yeasts ; Minisatellite ; Simple repetitive sequences ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: With the increase in the number of immunocompromised hosts, the number of fungal pathogens has increased markedly. Identification and classification, especially of yeast species and strains, is often difficult when based solely on phenotypic characteristics. Since it became clear that different fungal pathogens require specific treatment strategies, there is a need for simple, rapid and reliable methods to identify fungal isolates. Polymerase chain reaction (PCR) fingerprinting was successfully applied here to identify yeast isolates Microsatellite [(GTG)5; (GACA)4] and minisatellite [(5′GAGGGTGGCGGTTCT 3′), derived from the core-sequence of the phage M13] specific primers were used as single primers in the PCR to amplify hypervariable interrepeat DNA sequences from over 200 European, American and Australian clinical isolates within the genus Candida. Each species, represented by its type strain, could be identified by a specific multilocus pattern, allowing for the assignment of all the isolates to the appropriate species. Intra-species variation in the multilocus profiles was about 20% compared to inter-species variation, which was up to 80%. Anamorph-teleomorph pairs could be identified by highly homologous PCR fingerprint patterns. PCR fingerprinting was more discriminatory when compared with routinely used biochemical tests (Vitek YBC and API ID 32C). PCR fingerprinting has proven to be a powerful tool for the identification of medically important yeasts. It is rapid, sensitive, reliable, highly reproducible, stable in vitro and in vivo, and applicable to large-scale experiments. Potential applications include: yeast taxonomy, epidemiology, environmental surveys, and improvement of the diagnosis of mycotic diseases.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 2528-2535 
    ISSN: 0173-0835
    Keywords: Small GTPases ; Phagosome ; Two-dimensional polyacryl-amide gel electrophoresis ; Tetrahymena thermophila ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: In this study we purified phagosomes of the ciliated protozoan Tetrahymena thermophila to analyze aspects of the maturation pathway of phagocytotic vesicles. Phagosomes were labeled with magnetic microparticles and then purified in high amounts with the help of a permanent magnet. By combining a pulse-chase labeling protocol with the magnetic separation procedure we were able to isolate phagosomes of defined ages, which represent distinct stages of their maturation pathway. GTP-overlay assays showed that a set of small GTPases of the ras superfamily is associated with these phagosomes. Phagosomes isolated at different stages of maturation revealed a change in the pattern of the small GTPases. Some small GTPases identified by the GTPase overlay assays could be aligned to India ink stained protein spots in two-dimensional gels of isolated phagosomes. The results presented here are a first step to identify the members of small GTPases associated with phagosomes during their maturation pathway. Microsequencing of pooled polypeptides by mass-spectrometric techniques will identify the primary structure of these small GTPases.
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  • 9
    ISSN: 0173-0835
    Keywords: Platelet activation ; Protein phosphorylation ; Mass spectrometry ; Two-dimensional polyacrylamide gel electrophoresis ; Protein identification ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) is a powerful tool to separate complex protein mixtures including whole cell lysates. In combination with immunoblotting techniques or radioactive labeling techniques it is a fast and convenient way to demonstrate the presence of certain proteins or protein modifications. With the development of extremely sensitive analytical techniques such as matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS) or electrospray ionization (ESI)-MS, it has become possible to use 2-D gels not only as an analytical but also as a preparative tool. Starting with a number of spots excised from 2-D gels, a protein can be identified using different strategies involving enzymatic cleavage of the protein in the gel matrix, elution of the resulting peptides and analysis of these peptides by mass spectrometry. The obtained peptide mass fingerprint or fragment ion spectra from peptides can be used to screen protein or nucleic acid databases in order to identify the protein. We have used the techniques described above to identify proteins from human platelets which change their phosphorylation state following activation of platelets by thrombin. Platelets were radioactively labeled with [32P]orthophosphate and stimulated. Several protein spots in the observed range of 10-80 kDa and an isoelectric point of 3-10 showed a significant increase or decrease in phosphorylation. We present the results from the investigation of a spot group representing different isoforms and phosphorylation states of myosin light chain.
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  • 10
    ISSN: 0173-0835
    Keywords: Two-dimensional polyacrylamide gel electrophoresis ; Expression analysis ; Tetrahydrofolate synthesis ; Antibiotics ; Prokaryotes ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Two-dimensional electrophoresis was applied to the global analysis of the cellular response of Haemophilus influenzae to sulfamethoxazole and trimethoprim, both inhibitors of tetrahydrofolate synthesis. Deregulation of the synthesis rate of 118 proteins, involved in different metabolic pathways, was observed. The regulation of the genes involved in the metabolism of the amino acids methionine, threonine, serine, glycine, and aspartate was investigated in detail by analysis of protein synthesis and Northern hybridization. The results suggested that the synthesis of methionine biosynthetic enzymes in H. influenzae is regulated in a similar fashion as in Escherichia coli. A good correlation between the results obtained by Northern hybridization and quantification of protein synthesis was observed. In contrast to trimethoprim, sulfamethoxazole triggered the increased synthesis of the heat shock proteins DnaK, GroEL, and GroES.
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