The enzyme participates in bacterial electron transfer pathways in which dimethylsulfoxide (DMSO) is the terminal electron acceptor. It is composed of three subunits – DmsA contains a bis(guanylyl molybdopterin) cofactor and a [4Fe-4S] cluster, DmsB is an iron-sulfur protein, and DmsC is a transmembrane protein that anchors the enzyme and accepts electrons from the quinol pool. The electrons are passed through DmsB to DmsA and on to DMSO. The enzyme can also reduce pyridine-N-oxide and trimethylamine N-oxide to the corresponding amines with lower activity.