Involved in aliphatic epoxide carboxylation (PubMed:9405410, PubMed:10411892, PubMed:11939797). Catalyzes the addition of coenzyme M (CoM) to either R- or S-epoxypropane to form the thioether conjugate 2-hydroxypropyl-CoM (PubMed:10411892, PubMed:11939797). Catalyzes the reaction of CoM with R-epoxypropane at a rate approximately twice of that with S-epoxypropane (PubMed:10411892). The CoM analogs 2-mercaptopropionate, 2-mercaptoethanol and cysteine substitute poorly for CoM as the thiol substrate (PubMed:11939797). (R)-2-hydroxypropyl-coenzyme M = (R)-1,2-epoxypropane + coenzyme M (2S)-2-hydroxypropyl-coenzyme M = (S)-1,2-epoxypropane + coenzyme M Binds 1 zinc ion per subunit (PubMed:9405410, PubMed:11939797). Zinc plays a key role in activating an organic thiol substrate for nucleophilic attack on an alkyl-donating substrate (PubMed:11939797). Inhibited by methylepoxypropane (PubMed:9405410). Inhibited by the zinc chelator 4-(2-pyridylazo)resorcinol (PAR), in the presence of p- (hydroxymercuri)benzenesulfonic acid (PMPS), and by EDTA (PubMed:11939797). Not inhibited by the coenzyme M analog 2-bromoethanesulfonate (BES) (PubMed:20551308). kcat is 6.5 sec(-1) with R-epoxypropane as substrate. Optimum pH is 8.0-8.5. Alkene metabolism; propylene degradation. Homohexamer (PubMed:9405410). Component I of the aliphatic epoxide carboxylation complex together with components II, III and IV (PubMed:9405410, PubMed:10411892). Belongs to the vitamin-B12 independent methionine synthase family.