Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 22 (1980), S. 1895-1906 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Empirical estimations of H2O2 concentration in a system containing bovine liver catalase and continually supplied with H2O2 were done to evaluate the efficiency of the enzyme to cleave H2O2. It was found that the continuous addition of H2O2 leads to the formation of steady-state concentrations of H2O2 in the medium. At a constant catalase concentration both the level and the duration of the steady state are dependent on the flow rate of H2O2. The increase of the catalase concentration in the medium does not change the steady-state level, it merely leads to the maintenance of the steady state for longer durations. At higher flow rates of H2O2, no steady state could be maintained, even when catalase was present in high excess. The incomplete cleavage of H2O2 by catalase under these conditions is due to the low affinity of catalase toward H2O2 (high Km value, apparent Km = 0.1M H2O2) and to the rapid inactivation of the enzyme during the continuous addition of H2O2.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 22 (1980), S. 1877-1894 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The supply of heterotrophically growing suspensions of Alcaligenes eutrophus PHB-4 with oxygen formed by the continuous addition of H2O2 in the presence of bovine liver catalase was found to be restricted to well-defined conditions. The catalase-H2O2 system proved to be suitable during the growth at low cell densities equivalent to 2 g dry weight/liter. When under these conditions the oxygen concentration was held constant at 1.8 mg O2/liter, the cells grew for 6-8 hr at a rate almost identical to that observed with conventional aeration. However, aeration with H2O2 for longer durations (10-20 hr) and at higher cell densities (5-20 g dry weight/liter) led invariably to cell damage and retardation of growth. The impairment of growth observed during the oxygen supply by the catalase-H2O2 system was traced back to the formation of gradually increasing steady-state concentrations of H2O2 in the medium. Possible sites of cell damage by H2O2 such as membrane function, excretion and function of siderophores, and synthesis of cell polymers have been studied, and the cytotoxic mechanism of low concentrations of H2O2 was discussed.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A catalase has been purified from aerobically grown Escherichia coli K12. The enzyme exhibits unorthodox properties compared with catalyse from bovine liver and seems to be identical to hydroperoxidase II from E. coli. A mathematical model is presented which makes it possible to calculate the steady-state concentration of hydrogen peroxide in an open system. The model has been verified experimentally. It has been shown that the catalase from E. coli is better suited than the bovine liver enzyme for oxygen supply to cell suspensions using hydrogen peroxide.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 19 (1977), S. 413-424 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Oxygen has been supplied to suspensions of microorganisms kept under nitrogen by the addition of hydrogen peroxide. If catalase was present in the suspension and the flow was adjusted to the rate of oxygen consumption, the cells grew at rates identical to the controls incubated under air. The applicability of oxygen supply by hydrogen peroxide and its limits are discussed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...