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Enzymatic synthesis of L-ascorbic acid 3. L-galactono-Gamma-lactone oxidase from yeasts

Enzymatische Synthese von L-Ascorbinsäure 3. L-Galactono-Gamma-lactone-oxidase von Hefe
: Haller, C.-P.; Kulbe, K.-D.; Otto, M.

Deutsche Gesellschaft für Chemisches Apparatewesen, Chemische Technik und Biotechnologie e.V. -DECHEMA-, Frankfurt/Main:
Meeting of Biotechnologists '90
Weinheim: VCH Verlagsgesellschaft, 1990 (Dechema Biotechnology Conferences 4)
ISBN: 3-527-27997-0
S.233-236 : Abb.,Lit.
Deutsche Gesellschaft für Chemisches Apparatewesen (Jahrestagung) <1990, Frankfurt/Main>
Fraunhofer IGB ()
Ascorbinsäure; Bakterie; Hefe; saccharomyces

As part of an enzymatic process for ascorbic acid synthesis from uronic acids several microorganisms have been screened for L-aldonic acid-gamma-lactone oxidizing enzymes. 25 yeast strains with mitochondrial L-galactonic acid-gamma-lactone oxidase (GalOx) activity up to 50 mU/mg were detected. The enzyme from Saccaromyces exiguus was purified 260-fold by a 5 step procedure and characterized. L-gulono-gamma-lactone is also accepted as a substrate (30% relative activity). Ascorbic acid synthesis was studied in a fixed bed reactor. KM was changed from 0.25 mM to 1 mM by enzyme immobilization. A flow injection system based enzyme sensor was used. At higher substrate concentrations the production of ascorbic acid is limited by the availability of oxygen.