PURIFICATION AND PROPERTIES OF INDOLE 2,3-DIOXYGENASE FROM MAIZE LEAVES

Article abstract of DOI:10.1016/S0031-9422(00)84068-6

An indole 2,3-dioxygenase was purified ca 38-fold from maize leaves.The enzyme had an MW of about 98000, an optimum pH of 5.0 and the energy of activation was 9.1 kcal/mol.The K_m for indole was 1.4E-4 M.The enzyme was inhibited by diethyldithiocarbamate, salicylaldoxime and sodium dithionite.The inhibition by diethyldithiocarbamate was specifically reversed by Cu²⁺.The dialyzed enzyme was stimulated by Cu²⁺.Four atoms of oxygen were utilized in the disappearance of 1 mole of indole.Inhibition of the enzyme by -SH compounds and -SH group inhibitors, and their partial removal by Cu²⁺ only, suggested the involvement of -SH groups in binding of Cu²⁺ at the catalytic site.Key Word Index - Zea mays; Gramineae; maize leaf; indole oxidation; indole oxidase; indole 2,3-dioxygenase; purification; Cu²⁺; -SH groups.