| 摘要 |
PROBLEM TO BE SOLVED: To obtain the subject new enzyme having a specific optimum pH and a specific molecular weight, capable of dehydrogenation of serine and threonine at high temperatures in the presence of NAD(P) and useful e.g. for dehydrogenation at high temperatures, regeneration of coenzymes and assay of threonine and so on. SOLUTION: This new thermophilic threonine dehydrogenase enzyme is such one as to have an optimum pH of 7.5-10.0 and a molecular weight of 30,000-40,000 daltons (as measured by electrophoresis) and to be capable of dehydrogenation of serine and threonine in the presence of NAD or NADP at >90 deg.C and useful e.g. for enzymic dehydrogenation of hydroxy compounds at high temperatures, regeneration of coenzymes and specific assay of hydroxyamino acids, such as threonine and serine. The enzyme is obtained by preparing cDNA encoding the enzyme from sulfur-metabolizing thermophilic bacteria, such as Pyrococcus horikoshii (registration No. JCM 9974) through genetic cloning technique, integrating the cDNA into a vector, transforming it in host cells followed by its expression. |
