| 摘要 |
[PROBLEMS] To provide a thermostable L-ribose isomerase. [MEANS FOR SOLVING PROBLEMS] There is provided a thermostable L-ribose isomerase having physical and chemical properties such that molecular weight: 32,000 (SDS-PAGE), optimum temperature: 45°C, optimum pH: 9.0 (glycine-NaOH buffer) and temperature stability: being stable up to 45°C in heat treatment at pH 9.0 for 10 min, which thermostable L-ribose isomerase has the activity of isomerizing L-ribose into L-ribulose and reversely isomerizing L-ribulose into L-ribose. The thermostable L-ribose isomerase is an enzyme derived from Raoultella ornithinolytica MB426(NITE BP-277) (1). There is provided a method of conversion between aldose and ketose, characterized in that an aldose selected from among L-ribose, D-lyxose, D-talose, D-mannose, L-allose and L-gulose is acted on by the above thermostable enzyme to isomerize the aldose, thereby producing the corresponding ketose selected from among L-ribulose, D-xylulose, D-tagatose, D-fructose, L-psicose and L-sorbose, respectively, or alternatively a ketose selected from among L-ribulose, D-xylulose, D-tagatose, D-fructose, L-psicose and L-sorbose is acted on by the above L-ribose isomerase to isomerize the ketose, thereby producing the corresponding aldose selected from among L-ribose, D-lyxose, D-talose, D-mannose, L-allose and L-gulose, respectively. |
