Catalyzes the deamination of aminodeoxyfutalosine (AFL) into futalosine (FL), a step in the biosynthesis of menaquinone (MK, vitamin K2). To a lesser extent, can also deaminate 5'-methylthioadenosine. 6-amino-6-deoxyfutalosine + H(+) + H2O = futalosine + NH4(+) Binds 1 divalent metal cation per subunit. kcat is 1.28 sec(-1) with aminodeoxyfutalosine as substrate. kcat is 0.31 sec(-1) with 5'-methylthioadenosine as substrate. kcat is 0.017 sec(-1) with 5'-deoxyadenosine as substrate. Quinol/quinone metabolism; menaquinone biosynthesis. Belongs to the metallo-dependent hydrolases superfamily.