ISSN:
1750-3841
Quelle:
Blackwell Publishing Journal Backfiles 1879-2005
Thema:
Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
,
Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
Notizen:
Numerous microorganisms were screened for d-glucose isomerizing activity from soil by this laboratory. It was found that a strain of Streptomyces bikiniensis produced high activity of glucose isomerase in culture medium containing xylose or xylan as inducer. The cell bound glucose isomerase was prepared using cells of S. bikiniensis. The cell bound enzyme also efficiently catalyzes the isomerization of d-xylose and d-ribose and to a lesser extent L-rhamnose and d-arabinose to their respective ketoses. Isomerization of glucose to fructose by the enzyme was stimulated most effectively by Mg2+ and CO2+ combined or singly, and slightly by Mn2+. Cobalt and Mg2+ also inhibited thermal denaturation of the enzyme. The optimum pH for the enzyme was between 8 and 9, and optimum temperature was found to be 80°C. The enzyme is highly thermostable. The cell bound glucose isomerase was examined for isomerization of glucose to fructose in a batch system by incubating a mixture of the enzyme and various concentrations of glucose in 0.05M phosphate buffer, pH 7.2 containing 5 mM MgSO4 and 0.5 mM CoCl2 at various temperatures. It was found that maximum isomerization of glucose to fructose (50%) was reached when optimum concentration of enzyme and substrate was incubated at 70°C for 70 hr. The cell bound enzyme can be recovered after the operation and used for successive operations.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1111/j.1365-2621.1976.tb01177.x
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