The phototrophic bacterium strain Si4 induced ribitol dehydrogenase (EC when grown on ribitol- or xylitol-containing medium. This ribitol dehydrogenase was purified to apparent homogeneity by ammonium sulphate precipitation, affinity chromatography on Procion red, and chromatography on Q-Sepharose. For the native enzyme an isoelectric point of pH 6·1 and an apparent of 50000 was determined. SDS-PAGE yielded a single peptide band of 25000 suggesting a dimeric enzyme structure. The ribitol dehydrogenase was specific for NAD but unspecific as to its polyol substrate. In order of decreasing activity ribitol, xylitol, erythritol, D-glucitol and D-arabitol were oxidized. The pH optimum of substrate oxidation was 10, and that of substrate reduction was 6·5. The equilibrium constant of the interconversion of ribitol to D-ribulose was determined to be 0·33 nM at pH 7·0 and 25 °C. The -values determined for ribitol, ribulose, xylitol and NAD (in the presence of ribitol) were 6·3, 12·5, 77 and 0·077 mM, respectively. Because of the favourable for ribitol, a method for quantitative ribitol determination was elaborated.


Article metrics loading...

Loading full text...

Full text loading...


Most cited this month Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error