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  • 1990-1994  (2)
  • Biocatalysis  (1)
  • Electrical and Electronics Engineering  (1)
  • 1
    ISSN: 1476-5535
    Keywords: Lipase ; Bioconversion ; Biocatalysis ; Leukotriene receptor antagonist ; Verlukast ; Screening ; Pseudomonas aeruginosa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A search was implemented for a microbial lipase capable of bioconverting a diester (dimethyl 5-(3-(2-(7-chloroquinolin-2-yl)ethyl)phenyl)4,6-dithianon to its S-ester acid, an intermediate in the production of Verlukast (a leukotriene receptor antagonist). Required properties of the sought-after enzyme included a high enantiomeric selectivity (e.e. 〉98%), the formation of only trace amounts of diacid and a high bioconversion rate. This search yielded 57 lipase-producing microorganisms, 18 of which presented detectable bioconversion activity. Thirteen of these microbes were selected for further study based upon their lipase production level and enzyme stability at harvest. Despite their common enzymatic property, namely the hydrolysis of triglycerides, these lipase preparations presented diverse ester acid specific synthesis rates (from 〈0.01 μg/unit/h to 0.98 μg/unit/h) and diacid formation levels (from 0% to 35%). One of these microbes, identified asPseudomonas aeruginosa (strain MB 5001), was found to produce a lipase having all of the above-listed required properties. The initial fermentation process developed in shake flasks was rapidly and successfully scaled up in 23-liter labora bioreactors, achieving a maximum production of 35 units/ml of lipase after 48 h of cultivation.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 3 (1990), S. 99-110 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: A procedure is described for estimating various parameters governing the diffusion of impurities in semiconductors; these parameters are required for a number of explicit numerical models of non-linear diffusion in III-V crystals. The method is based on an analytical solution of the continuum equivalent of a discrete numerical model due to Zahari and Tuck and provides a systematic procedure for analysing experimental data to yield predictions for the coefficient of diffusion of the impurity, the coefficient of self-diffusion of the host material, the bulk equilibrium vacancy concentration and, under conditions of “dissociation” pressure, the surface vacancy concentration. Application of the procedure to two sets of independent experimental data provided reasonably consistent values of the parameters.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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