Fructoselysine-6-kinase (sometimes also called fructoselysine kinase) is a kinase enzyme.
It phosphorylates fructoselysine on the fructose residue's 6-carbon to form fructoselysine-6-phosphate, as the first step to breaking it down to glucose-6-phosphate and lysine for use as a food source. The second step is accomplished by the enzyme fructoselysine-6-phosphate deglycase.[1]
In E. coli, both enzymes are located on the frl (fructoselysine) operon in order to be transcribed simultaneously. In this context it is known as gene 'frlD' and fructoselysine 6-phosphate deglycase as 'frlB'.[2]