Purification and characterization of isocitrate lyase from the wood-destroying basidiomycete Fomitopsis palustris grown on glucose.
Isocitrate lyase (EC 4.1.3.1), a key enzyme in the glyoxylate cycle, was purified 76-fold with 23% yield as an electrophoretically homogeneous protein from the wood-destroying basidiomycete Fomitopsis palustris grown on glucose. The native enzyme has a molecular mass of 186 kDa, consisting of three identical subunits of 60 kDa. The K(m) for DL-isocitrate was found to be 1.6 mM at the optimum pH (7.0). The enzyme required Mg(2+) (K(m) 92 microM) and sulfhydryl compounds for optimal activity. The enzyme activity was strongly inhibited by oxalate and itaconate with a K(i) of 37 and 68 microM, respectively. The inhibition by the glycolysis and tricarboxylic acid cycle intermediates and related compounds suggested that the isocitrate lyase was a regulatory enzyme playing a crucial role in the fungal growth.
Munir
Erman
E
Wood Research Institute, Kyoto University, Uji, Kyoto 611-0011, Japan.
Hattori
Takefumi
T
Shimada
Mikio
M
D001487:Basidiomycota / Q000201:enzymology* / Q000254:growth & development; D003470:Culture Media; D005947:Glucose / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007522:Isocitrate Lyase / Q000302:isolation & purification* / Q000378:metabolism; D007523:Isocitrates / Q000378:metabolism; D008274:Magnesium / Q000378:metabolism; D013438:Sulfhydryl Compounds / Q000494:pharmacology; D014934:Wood
D003470:Culture Media; D007523:Isocitrates; D013438:Sulfhydryl Compounds; C034219:isocitric acid; D007522:Isocitrate Lyase; D008274:Magnesium; D005947:Glucose