원문정보
초록
영어
L-Rhamnose (6-deoxy-L-mannose) is a constituent of many glycosides in a variety of plants. For L-rhamnose degradation, two distinct routes involving phosphorylated or non-phosphorylated intermediates are reported in bacteria and fungi. However, the enzymes participating in the non-phosphorylated L-rhamnose pathway which transforms L-rhamnose to L-lactaldehyde and
pyruvate, are not yet identified and characterized. In the present work, we demonstrated the 2-keto-3-deoxy-L-rhamnonate (KDR) aldolase activity in the thermoacidophilic archaeaon Thermoplasma acidophilum and some of its properties were studied. To identify and characterize the KDR aldolase, its coding gene was cloned into the pRSET expression vector and expressed in E. coli BL21 (DE3). The molecluar mass of the recombinant protein was
determined to be approximately 34 kDa, which is closely matched to the calculated theoretical value (33,770.03 Da). KDR aldolase reversibly catalyzes an aldol cleavage of KDR to L-lactaldehyde and pyruvate. To assay the activity of KDR aldolase, we first measured 2-keto-3-deoxy-aldonate formation from alpha-hydroxyaldehydes (lactaldehyde, glyceraldehyde,
glycolaldehyde) and pyruvate. The recombinant protein showed the highest aldolase activity towards L-lactaldehyde and pyruvate. Aldolase cleavage activity toward KDR was also observed, indicating that T. acidophilum has the ability to utilize L-rhamnose as a carbon source.