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  • Chemistry  (43)
  • Atomic, Molecular and Optical Physics  (11)
  • Hansenula polymorpha  (5)
  • Magnetism
  • 1980-1984  (59)
  • 1
    Electronic Resource
    Electronic Resource
    Regulation of the synthesis of methanol oxidizing enzymes inKloeckera sp. 2201 andHansenula polymorpha, a comparison (1982)
    Springer
    Archives of microbiology 131 (1982), S. 174-175 
    Details
    ISSN: 1432-072X
    Keywords: Hansenula polymorpha ; Kloeckera sp. 2201 ; Methanol ; Glucose ; Methanol dissimilating enzymes ; Regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A comparative study was made of the regulation of the synthesis of methanol dissimilating enzymes inkloeckera sp. 2201 andHansenula polymorpha using chemostat and batch growth conditions and methanol or glucose as carbon sources. During growth in methanol-limited chemostat cultures similar enzyme patterns for alcohol oxidase, catalase, formaldehyde dehydrogenase and formate dehydrogenase in the two yeasts were found. When growing in batch culture with glucoseH. polymorpha, but notKloeckera sp. 2201, was found to produce ethanol which might affect the synthesis of these enzymes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01054002
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  • 2
    Electronic Resource
    Electronic Resource
    Active-site α-helix in papain and the stability of the ion pair RS- ··· ImH+. Ab initio molecular orbital study (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 651-671 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ab initio MO calculations, using both minimal (STO-3G) and extended (Roos-Siegbahn) basis sets are reported for the systems methanethiol-imidazole, methanethiol-imidazole-formaldehyde, and methanethiol-imidazole-formamide, which, together with a point-change representation of a long α-helix, form models for the active site of papain. It is shown that the large electric field exerted by the helix in the active-site region is responsible for the presence of the essential residues Cys 25 and His 159 in the form of an ion pair RS- ··· ImH+, which is crucial for a recently proposed mechanism for the catalytic action of the enzyme. Also, an explanation is given for the anomalies in measured pK values for these residues. Detailed studies on the (sub)systems show that minimal basis sets lack the flexibility necessary for describing the type of proton transfer involved. We conclude that α-helices are essential parts of enzymes and that they play a significant role in the catalytic process.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170407
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  • 3
    Electronic Resource
    Electronic Resource
    Mixed substrate growth of methylotrophic yeasts in chemostat culture: Influence of the dilution rate on the utilisation of a mixture of glucose and methanol (1982)
    Springer
    Archives of microbiology 131 (1982), S. 8-13 
    Details
    ISSN: 1432-072X
    Keywords: Hansenula polymorpha ; Kloeckera sp. 2201 ; Mixed substrate utilisation ; Chemostat ; Induction ; Repression ; Methanol ; Glucose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The growth of Hansenula polymorpha and Kloeckera sp. 2201 with a mixture of glucose and methanol (38.8%/61.2%, w/w) and the regulation of the methanol dissimilating enzymes alcohol oxidase, catalase, formaldehyde dehydrogenase and formate dehydrogenase were studied in chemostat culture, as a function of the dilution rate. Both organisms utilized and assimilated glucose and methanol simultaneously up to dilution rates of 0.30 h-1 (H. polymorpha) and 0.26h-1, respectively (Kloeckera sp. 2201) which significantly exceeded μmax found for the two yeasts with methanol as the only source of carbon. At higher dilution rates methanol utilisation ceased and only glucose was assimilated. Over the whole range of mixed-substrate growth both carbon sources were assimilated with the same efficiency as during growth with glucose or methanol alone. In cultures of H. polymorpha, however, the growth yield for glucose was lowered by the unmetabolized methanol at high dilution rates. During growth on both carbon sources the repression of the synthesis of all catabolic methanol enzymes which is normally caused by glucose was overcome by the inductive effect of the simultaneously fed methanol. In both organisms the synthesis of alcohol oxidase was found to be regulated differently as compared to catalase, formaldehyde and formate dehydrogenase. Whereas increasing repression of the synthesis of alcohol oxidase was found with increasing dilution rates as indicated by gradually decreasing specific activities of this enzyme in cell-free extracts, the specific activities of this enzyme in cell-free extracts, the specific activities of catalase and the dehydrogenases increased with increasing growth rates until repression started. The results indicate similar patterns of the regulation of the synthesis of methanol dissimilating enzymes in different methylotrophic yeasts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00451491
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  • 4
    Electronic Resource
    Electronic Resource
    Regulatory flexibility of methylotrophic yeasts in chemostat cultures: Simultaneous assimilation of glucose and methanol at a fixed dilution rate (1982)
    Springer
    Archives of microbiology 131 (1982), S. 1-7 
    Details
    ISSN: 1432-072X
    Keywords: Hansenula polymorpha ; Kloeckera sp. 2201 ; Chemostat ; Mixed substrates ; Glucose ; Methanol ; Growth yields ; Enzyme regulation ; Dissimilatory enzymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The influence of the composition of methanol/glucose-mixtures as only sources of carbon and energy on growth and regulation of the synthesis of enzymes involved in methanol-dissimilation was studied under chemostat conditions at a fixed dilution rate with the methylotrophic yeasts Hansenula polymorpha and Kloeckera sp. 2201. Both carbon sources were found to be utilized completely independently of the composition of the C1/C6 mixture. Using mixtures of 14C-labelled methanol and glucose the growth yield for glucose was found to be constant for all C1/C6-mixtures tested and both yeasts. The growth yield for methanol, however, was reduced by up to 25% when the proportion of methanol in the inflowing medium was lower than 20% (w/w with respect to glucose) for H. polymorpha and 50% (w/w with respect to glucose) for Kloeckera sp. 2201 respectively. During growth with C1/C6-mixtures containing higher C1-proportions of methanol regular growth yields for methanol were recorded which corresponded to the growth yields found with methanol as the only carbon source. The regulation of the synthesis of the enzymes of the dissimilatory pathway for methanol was found to be under multiple control. Although glucose was present in the medium methanol had a positive effect on the synthesis of these enzymes. Thus, in addition to derepression induction by methanol was also observed. This inductive effect was found to increase with increasing proportions of methanol in the mixture. Depending on the enzyme, 10–40% methanol in the mixture resulted in a maximal induction with enzyme specific activities equal to those found in cells grown with methanol as the only carbon source. No further enhancements in enzyme specific activities were observed during growth on mixtures containing more than 40% methanol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00451490
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  • 5
    Electronic Resource
    Electronic Resource
    Methanol metabolism in yeasts: Regulation of the synthesis of catabolic enzymes (1980)
    Springer
    Archives of microbiology 124 (1980), S. 115-121 
    Details
    ISSN: 1432-072X
    Keywords: Derepression ; Catabolite inactivation ; Alcohol oxidase ; Catalase ; Formaldehyde dehydrogenase ; Formate dehydrogenase ; Hansenula polymorpha ; Kloeckera sp. 2201 ; Peroxisomes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The regulation of the synthesis of four dissimilatory enzymes involved in methanol metabolism, namely alcohol oxidase, formaldehyde dehydrogenase, formate dehydrogenase and catalase was investigated in the yeasts Hansenula polymorpha and Kloeckera sp. 2201. Enzyme profiles in cell-free extracts of the two organisms grown under glucose limitation at various dilution rates, suggested that the synthesis of these enzymes is controlled by derepression — represion rather than by induction — repression. Except for alcohol oxidase, the extent to which catabolite repression of the catabolic enzymes was relieved at low dilution rates was similar in both organisms. In Hansenula polymorpha the level of alcohol oxidase in the cells gradually increased with decreasing dilution rate, whilst in Kloeckera sp. 2201 derepression of alcohol oxidase synthesis was only observed at dilution rates below 0.10 h−1 and occurred to a much smaller extent than in Hansenula polymorpha. Derepression of alcohol oxidase and catalase in cells of Hansenula polymorpha was accompanied by synthesis of peroxisomes. Moreover, peroxisomes were degraded with a concurrent loss of alcohol oxidase and catalase activities when excess glucose was introduced into the culture. This process of catabolite inactivation of peroxisomal enzymes did not affect cytoplasmic formaldehyde dehydrogenase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00427715
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  • 6
    Electronic Resource
    Electronic Resource
    Regulation of protein synthesis in methylotrophic yeasts: Repression of methanol dissimilating enzymes by nitrogen limitation (1982)
    Springer
    Archives of microbiology 131 (1982), S. 95-101 
    Details
    ISSN: 1432-072X
    Keywords: Chemostat ; Nitrogen limitation ; Hansenula polymorpha ; Kloeckera sp. 2201 ; Carbon limitation ; Repression ; Methanol dissimilating enzymes ; Shift experiment ; Catabolite inactivation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The influence of nitrogen limitation on the regulation of the methanol oxidizing enzymes alcohol oxidase, catalase, formaldehyde dehydrogenase and formate dehydrogenase in the two methylotrophic yeastsHansenula polymorpha andKloeckera sp. 2201 was studied in continuous culture. When shifted from carbon-limited growth conditions (with a mixture of glucose and methanol as carbon sources) to a nitrogen-limited environment both cultures were found to go through a transition phase where neither enhanced residual concentrations of the nitrogen source nor of one of the two carbon sources could be detected in the supernatant. As soon as nitrogen became a limiting substrate an immediate reorganisation of the cell composition was initiated: protein content of the cells dropped to approximately 40% of its initial value, glycogen was synthesized and the enzyme composition of the cells was changed. The peroxisomal enzymes alcohol oxidase and catalase in both organisms and the two dehydrogenases for formaldehyde and formate in cells ofKloeckera sp. 2201 were subject to degradation (catabolite inactivation). The measured rates of inactivation indicated that in cells ofH. polymorpha this process might be limited to peroxisomes, whereas inKloeckera sp. 2201 the degradation was found to affect peroxisomal as well as cytoplasmic enzymes. In contrast to methanol dissimilating enzymes the net rate of synthesis of hexokinase, glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase was not affected by this process but those enzymes were synthesized with increased rates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01053988
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  • 7
    Electronic Resource
    Electronic Resource
    A quantitative description of the growth of Saccharomyces cerevisiae CBS 426 on a mixed substrate of glucose and ethanol (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 22 (1980), S. 2031-2043 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Saccharomyces cerevisiae CBS 426 was grown aerobically in continuous culture with a mixture of glucose and ethanol as the carbon source. The flows of biomass, glucose, ethanol, oxygen, and carbon dioxide were measured. A model for growth with two substrates was derived. Application of this model to the above-mentioned system yielded values for YATP and P/O. The joint confidence regions for these parameters were calculated. The relevance to industrial production of bakers' yeast is discussed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260221004
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  • 8
    Electronic Resource
    Electronic Resource
    Abriebfestigkeiten der Korrosionsschutzbeschichtungen im Stahlwasserbau (1980)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 31 (1980), S. 866-869 
    Details
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Wear-resistance of anti-corrosion coatings in hydraulic steel constructionsDIN 55 928 gives rules for the protection of steel structures from corrosion by organic and metallic coatings. The durability against abrasion of such coatings is classified in part 5, table 8, columns 9-11, of this DIN. A notice to these columns gives indication of an abrasion-machine developed by the Bundesanstalt für Wasserbau in Karlsruhe.Giving the best results, this machine for testing the mechanic durability was chosen out of a number of testing systems. The result is an abrasion value (Abriebwert).This value enables us to classify the coatings in accordance with their durability.The abrasion machine, its main dimensions and its working are described.
    Notes: In der Tabelle 8 des Teils 5 der DIN 55 928 - Korrosionsschutz von Stahlbauten durch Beschichtungen und Überzüge - wird in Spalte 9-11 die mechanische Beanspruchung der Beschichtungen klassifiziert und in einer Bemerkung dazu auf ein Prüfgerät hingewiesen, das bei der Bundesanstalt für Wasserbau in Karlsruhe entwickelt wurde.Das Prüfgerät ist das Ergebnis einer längeren Entwicklung; es ermöglicht die Angabe eines „Abriebwertes“ als Abstufung der Belastbarkeit von Beschichtungssystemen.Die Entwicklung des Prüfgerätes wird dargelegt und das Prüfgerät sowie der Prüfvorgang beschrieben.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19800311105
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  • 9
    Electronic Resource
    Electronic Resource
    Schwingungsrißkorrosion an plasmanitriertem stahlAuszugsweise vorgestellt auf der Hauptversammlung der Deutschen Gesellschaft für Metallkunde 1982 in Villach (1982)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 33 (1982), S. 647-653 
    Details
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Corrosion fatigue of plasmanitrided steelThe effect of plasma-nitriding of steel 34 CrAlMo 5 on corrosion fatigue has been investigated in cyclic torsion. The tests were conducted in air, tap water and artifical sea water. Crack initiation and propagation have been studied by means of metallographic and fractographic methods to identify the fatigue mechanisms.Main results may be summarized as follows: The fatigue strength increases by about 40% due to plasma-nitriding over that of nonnitrided steel when tested in air. Even in corrosion environment plasma-nitriding improves remarkably the fatigue strength. The torsional fatigue strength of plasmanitrided specimen is not affected by the presence of tap water. In artifical sea water the distinct fatigue limit disappears. However, the fatigue life of the plasmanitrided specimen increases by factor of 10 compared with that of non-nitrided specimen. The reasons for this improvement were discussed by considering the mechanical and metallurgical aspects of the problems.
    Notes: Das Schwingungsrißkorrosionsverhalten von plasmanitriertem Stahl 34 CrAlMo 5 wurde in Torsionswechselversuchen an Luft, in Leitungswasser und in künstlichem Meerwasser untersucht. Rißbildung und Rißausbreitung wurden mittels metallographischer und fraktographischer Untersuchungsmethoden analysiert. Die Ergebnisse lassen sich folgendermaßen zusammenfassen: Durch das Plasmanitrieren wird an Luft eine Steigerung der Dauerfestigkeit um 40% gegenüber dem unbehandelten Zustand erreicht. Auch bei Einwirkung eines korrosiven Mediums bewirkt die Plasmanitrierschicht eine wesentliche Verbesserung des Dauerschwingverhaltens. Die Torsionswechselfestigkeit des plasmanitrierten Werkstoffes wird von einer Leitungswasserumgebung nicht beeinträchtigt. Im künstlichen Meerwasser existiert sowohl im unbehandelten als auch im plasmanitrierten Werkstoffzustand keine Dauerfestigkeit. Die Lebensdauer des plasmanitrierten Werkstoffes ist jedoch um eine Zehnerpotenz größer als die des unbehandelten Werkstoffes. Für die dargestellten Versuchsergebnisse werden verschiedene Deutungsmöglichkeiten diskutiert.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19820331202
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  • 10
    Electronic Resource
    Electronic Resource
    Electronic states near dislocations in transition metals: An application of quantum chemistry in technology (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 18 (1980), S. 575-582 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper outlines a model for calculating the localized states of a 〈 100 〈 edge dislocation in α-Fe. The model used for the calculations is based on the multiple-scattering model (SCF-X α-SW). The purpose of this research is twofold: (1) To determine changes in electronic structure of the lattice near the core region of defects in α-Fe. (2) The variations of hydrostatic pressure about an edge dislocation produce a rearrangement of the conduction electrons. The question is what electrical interaction might be expected between a dislocation and a charged solute atom. The calculations show that the electrons tend to flow away from the compression side toward the dilated regions. The electrical contribution to the binding energy of a solute atom and a dislocation in α-Fe is of the order of 0.01 Ry/electronic unit charge of the atom.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560180229
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