1.14.15.34	physiological function	the tylH mutant, which is blocked in the oxidation of C-23 methyl to hydroxymethyl, is capable of carrying out all other biosynthetic steps except addition of 6-deoxy-D-allose and subsequent O-methylations and produces the biologically active compound 23-deoxydemycinosyl tylosine. A tyID tylH lacking double mutant, blocked specifically in the biosynthesis of 6-deoxy-D-allose and in specific oxidation of tylactone, accumulates 23-deoxydemycinosyl tylosin and therefore cannot oxidize the C-23 methyl position of lactone	726686