Enzymatic production of L-serine.
Biotechnol Bioeng
; 28(6): 857-67, 1986 Jun.
Article
en En
| MEDLINE
| ID: mdl-18555404
ABSTRACT
Serine hydroxymethyltransferase (SHMT) in the form of crude extract form a recombinant strain of Klebsiella aerogenes was used to study the production of L-serine from glycine and formaldehyde (HCHO). SHMT activity linearly increased with temperature (30-50 degrees C). Addition of exogenous cofactors, tetrahydrofolic acid and pyridoxal-phosphate, significantly increased SHMT activity. The pH optimum of the SHMT catalyzed L-serine synthesis step was between 8.0 and 8.5. The K(m) for glycine was 11.6mM at 37 degrees C and pH 8.0. A 87% molar conversion of glycine to serine was obtained at equilibrium (37 degrees C, pH 8.0). Tetrahydrofolic acid was stabilized by maintaining the redox potential of the reaction solution below -330 mV through the addition of a reducing reagent such as beta-mercaptoethanol. SHMT stability was very sensitive to HCHO concentration. By carefully balancing the HCHO feed rate against the enzymatic bioconversion rate in order to keep HCHO concentration low, a serine titer of 160 g/L was achieved, the residual glycine concentration was reduced to 40 g/L, a 70% molar conversion of glycine with quantitative yield was obtained, and the overall serine productivity was 5.2 g/L/h.
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01-internacional
Base de datos:
MEDLINE
Idioma:
En
Revista:
Biotechnol Bioeng
Año:
1986
Tipo del documento:
Article
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EEUU
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ESTADOS UNIDOS
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ESTADOS UNIDOS DA AMERICA
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EUA
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UNITED STATES
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UNITED STATES OF AMERICA
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USA