• In enzymology, a macrocin O-methyltransferase (EC 2.1.1.101) is an enzyme that catalyzes the chemical reaction S-adenosyl-L-methionine + macrocin ⇌ {\displaystyle \rightleftharpoons } S-adenosyl-L-homocysteine + tylosin Thus, the two substrates of this enzyme are S-adenosyl methionine and macrocin, whereas its two products are S-adenosylhomocysteine and tylosin. (wikipedia.org)