Catalyzes the hydrolysis of futalosine (FL) to dehypoxanthine futalosine (DHFL) and hypoxanthine, a step in the biosynthesis of menaquinone (MK, vitamin K2). Is highly specific to futalosine since it does not accept aminodeoxyfutalosine (AFL), or any structurally related nucleotides and nucleosides as substrate. futalosine + H2O = dehypoxanthine futalosine + hypoxanthine No enhancing of inhibitory effects are observed with divalent metal ions. Slightly inhibited by hypoxanthine. kcat is 1.02 sec(-1). Optimum pH is 4.5. Optimum temperature is 80 degrees Celsius. Quinol/quinone metabolism; menaquinone biosynthesis. Homotetramer. Belongs to the PNP/UDP phosphorylase family. Futalosine hydrolase subfamily.