title: Evidence for the existence of meta and para directing O-methyltransferases in tobacco cell cultures.
abstract: The O-methyltransferase of tobacco cell culture was resolved to its meta and para directing forms by chromatography on DEAE-cellulose. Despite similarities in molecular weights and pI values of the two forms, however, evidence from pH optima, SH-group inhibitors, methylation ratios, SDS-acrylamide gels and mixed substrate experiments indicates the existence of two discrete enzymes acting at the meta and para positions of caffeic acid and quercetin, respectively; though the latter enzyme was less substrate specific than its meta counterpart.
mesh_terms: D002478:Cells, Cultured; D008780:Methyltransferases / Q000302:isolation & purification / Q000378:metabolism*; D008970:Molecular Weight; D010944:Plants / Q000201:enzymology*; D010947:Plants, Toxic; D013379:Substrate Specificity; D014026:Nicotiana / Q000201:enzymology
chemical_list: D008780:Methyltransferases