Novel reactions of l-rhamnose isomerase from Pseudomonas stutzeri and its relation with d-xylose isomerase via substrate specificity

Characterization ofMesorhizobium lotiL-Rhamnose Isomerase and Its Application toL-Talose Production

“…L-RhI from M. loti showed broad substrate specificity and recognized sugar substrates at the C2 and C3 positions but not at the C4 and C5 positions, similarly to what was observed for P. stutzeri. 10) No formation of other aldoses via a corresponding ketose was observed when the aldose substrate described above was used, differently to what was observed for P. stutzeri L-RhI (data not shown). 10) The AARs of M. loti L-RhI (Glu219, Lys221, Asp254, His257, His281, Asp289, Asp291, Asp327), which interacted with C1, C2, and C3 positions of the sugar substrate, were conserved.…”

“…10) No formation of other aldoses via a corresponding ketose was observed when the aldose substrate described above was used, differently to what was observed for P. stutzeri L-RhI (data not shown). 10) The AARs of M. loti L-RhI (Glu219, Lys221, Asp254, His257, His281, Asp289, Asp291, Asp327), which interacted with C1, C2, and C3 positions of the sugar substrate, were conserved. 11) This confirms a similarity of substrate specificity between M. loti L-RhI and P. stutzeri L-RhI, but X-ray crystallography determination is necessary to provide further evidence of this.…”

“…The K m and k cat /K m values of M. loti L-RhI as compared with other known L-RhIs, showed affinity and catalytic efficiency similar to D-allose (Table 2), but the kinetic parameters of M. loti L-RhI to D-allose and L-talose, compared with the phospho-isomerases were significantly different (Table 2). 8,10,20,21) These results suggest that the catalytic mechanisms of L-RhI and phospho-isomerase may be different. Recombinant L-RhI from M. loti was applied to produce L-talose from L-tagatose.…”

“…The L-RhI of P. stutzeri and glucose-6-phosphate isomerase of P. furiosus has produced L-talose and L-galactose from L-tagatose. 10,13,20) Immobilized M. loti L-RhI and the remaining L-tagatose after separation might be utilized in further reactions. Therefore, our results indicate that this enzyme can be applied in the largescale production of L-talose.…”

Polyol Conversion Specificity ofBacillus pallidus

“…L-Rhamnose isomerase derived from Pseudomonas stutzeri showed broad substrate specificity for various aldoses and ketoses, while the same enzyme derived from Escherichia coli showed high substrate specificity, and it does not act on D-allose. 10) In this study, we found four reactions that were catalyzed by this enzyme from B. pallidus (Fig. 3).…”