An ATP-dependent kinase that phosphorylates glucose to make glucose-6-phosphate, not active on fructose, galactose or mannose. Restores glucose kinase activity in E.coli glk mutants. ATP + D-glucose = ADP + D-glucose 6-phosphate + H(+) Optimum temperature is 32 degrees Celsius. Enzyme is stable up to 40 degrees Celsius. Constitutively expressed, activity is maximal at the end of vegetative growth and declines during stationary phase when grown in rich broth (LB) (at protein level). Expressed in a similar fashion in minimal medium containing glucose, fructose, trehalose, maltose or sucrose. Loss of glucokinase activity, no growth phenotype on glucose, fructose, maltose, sucrose or trehalose-containing minimal media. Belongs to the ROK (NagC/XylR) family.