Catalyzes the phosphorylation of the ketose sugar fructose to fructose-1-phosphate. ATP + beta-D-fructose = ADP + beta-D-fructose 1-phosphate + H(+) Requires potassium. Inhibition by ADP (By similarity). Carbohydrate metabolism; fructose metabolism. Homodimer. Belongs to the carbohydrate kinase PfkB family.