The purification and properties of l-rhamnulokinase

l-Rhamnulokinase (ATP:l-rhamnulose phosphotransferase, EC 2.7.1.5.) has been purified 34-fold from extracts of Escherichia coli K40. The purified enzyme catalyzes the phosphorylation of l-rhamnulose, but not of l-rhamnose, in the presence of Mg²⁺ and adenosine 5′-triphosphate. Uridine triphosphate, cytidine 5′-triphosphate, guanosine 5′-triphosphate, and thymidine triphosphate also can act as phosphoryl donors, but less well than adenosine 5′-triphosphate.

The product of the phosphorylation of l-rhamnulose by the enzyme has been isolated and characterized by periodic acid oxidation studies as l-rhamnulose i-phosphate.