Partial Characterisaton of 1,3,6,8- TctrahydroxynaphthaJene Reductase from Verticillium dahliae brm -1

Abstract

1,3,6,8-tetrahydroxynaphtha1ene reductase which isolated from Veritcillium dahliac brm-l , was purified and partially characterised. The result showed that optimum pH and temperature of the enzyme were pH 7 and 30"C respectively. The enzyme was stable upto 40"C, above that temperature enzyme activity slowly declined and inactivated above 60"C. The probable primary sequence of the Nterminus of the enzyme was A1a-Lys-J1e-Tye-Asp-Asp-Arg-Leu-Thr-G1y respectively. Met and Arg are the other option for the first and 4th amino acids respectively. 1,3dihdroxynaphtha1ene is a new substrate for the enzyme and the substrate specificity of the enzyme for 1,3,6,8-tetrydroxynaphtha1ene (T4HN), 1,3,8- trihydroxynaphthalene (T3HN) and 1,3-dihydroxynaphthalene (I ,3-DHN) is as follows. T4I-1N>T3HN> 1,3-DHN Emodin appear to be inhibitor for the enzyme whereas 1,3-dihydoxy-6,8- dimethoxynaphthalene possibly acts as a competitive inhibitor as well as a weaker substrate for the enzyme.