METABOLISM OF PENTOSES AND PENTITOLS BY AEROBACTER AEROGENES. 3. PHYSICAL AND IMMUNOLOGICAL PROPERTIES OF PENITOL DEHYDROGENASES AND PENTULOKINASES.

Mortlock, R. P. (Michigan State University, East Lansing), D. D. Fossitt, D. H. Petering, and W. A. Wood. Metabolism of pentoses and pentitols by Aerobacter aerogenes. III. Physical and immunological properties of pentitol dehydrogenases and pentulokinases. J. Bacteriol. 89:129-135. 1965.-Four pentulokinases and three pentitol dehydrogenases were purified from Aerobacter aerogenes PRL-R3, and the properties of the enzymes within each family were compared. d-Ribulokinase was purified from cells grown on ribitol, d-arabitol, and xylitol, and from a mutant constitutive for ribitol dehydrogenase; d-xylulokinase, from cells grown on d-xylose and xylitol; l-ribulokinase, from cells grown on l-arabinose; and l-xylulokinase, after growth on l-xylose. Similarly, ribitol dehydrogenase was purified after growth on ribitol, d-arabinose, and xylitol, and from the ribitol dehydrogenase-constitutive mutant. d-Arabitol dehydrogenase was obtained after growth on d-arabitol or d-xylose, and xylitol dehydrogenase was obtained after growth on xylitol. Except for l-xylulokinase, which also had a different S(20) value, the pentulokinases had identical pH optima, K(m) for the ketopentose, and sedimentation constants, and fractionated identically by a number of procedures. These kinases could be distinguished only by their substrate and immunological specificity. Ribitol dehydrogenase and d-arabitol dehydrogenase could be distinguished by several properties, but the properties of xylitol dehydrogenase were always similar to ribitol dehydrogenase. In all cases, individual kinases or dehydrogenases produced by different inducers had identical properties. These data constitute evidence against multiple forms of the same enzyme being produced by different inducers and against the dehydrogenase family containing essentially identical proteins differing only at the active site. For the kinases, three of the four appear to differ only at the active site.