Involved in the biosynthesis of dTDP-alpha-D-desosamine, a sugar found in several bacterial macrolide antibiotics. Catalyzes the SAM-dependent deamination of dTDP-4-amino-4,6-deoxyglucose (dTDP-viosamine) to yield dTDP-3-keto-4,6-deoxyglucose. It can also catalyze the oxidative dehydrogenation of the non-physiological substrate dTDP-D-quinovose to dTDP-3-keto-6-deoxy-d-glucose. It can also deaminate dTDP-3-amino-3,6-deoxyglucose. AH2 + dTDP-4-amino-4,6-dideoxy-alpha-D-glucose + S-adenosyl-L-methionine = 5'-deoxyadenosine + A + dTDP-3-dehydro-4,6-dideoxy-alpha-D-glucose + H(+) + L-methionine + NH4(+) Binds 1 [4Fe-4S] cluster. kcat is 0.017 sec(-1) for ammonia-lyase activity with dTDP-viosamine as substrate (at pH 8 and 25 degrees Celsius). Monomer. The reaction starts by the transfer of an electron from the [4Fe-4S] cluster to S-adenosyl-L-methionine, spliting it into methionine and the radical 5-deoxyadenosin-5'-yl, which attacks the sugar substrate. Belongs to the radical SAM superfamily. DesII family.