Plays a role in the catabolism of L-fucose, a sugar that is part of the carbohydrates that are attached to cellular glycoproteins. Catalyzes the dehydration of L-fuconate to 2-keto-3-deoxy-L-fuconate by the abstraction of the 2-proton to generate an enediolate intermediate that is stabilized by the magnesium ion (PubMed:24697329). L-fuconate = 2-dehydro-3-deoxy-L-fuconate + H2O Binds 1 Mg(2+) ion per subunit. kcat is 0.5 sec(-1) for L-fuconate. kcat is 0.3 sec(-1) for L-galactonate. kcat is 0.3 sec(-1) for L-arabinonate. kcat is 0.04 sec(-1) for D-arabinonate. kcat is 0.002 sec(-1) for D-ribonate. Could be sumoylated. Belongs to the mandelate racemase/muconate lactonizing enzyme family. ENOSF1 subfamily. Was originally (PubMed:8493092) identified as a gene coding for an antisense RNA to thymidylate synthase, and was proposed to down-regulate TYMS activity (PubMed:8869746), possibly by promoting the degradation of TYMS mRNA via an antisense RNA-based mechanism (PubMed:12084460). Truncated N-terminus. Truncated N-terminus.