PURIFICATION AND PARTIAL CHARACTERIZATION OF AN INTRACELLULAR NADH - QUINONE OXIDOREDUCTASE FROM PHANEROCHAETE-CHRYSOSPORIUM

Phanerochaete chrysosporium produced several intracellular NADH: quinone oxidoreductases under agitated, nitrogen-limited cultivation conditions. One of the quinone reductases was purified and shown to have a molecular mass of 69 kDa by SDS-PAGE, while the molecular mass determined by gel filtration was 47 kDa. This reductase was separated by IEF into four protein bands, each with quinone reductase activity. The isoelectric points of the proteins were 5.7, 5.9, 6.0 and 6.3. The proteins reduced several quinones to the corresponding hydroquinones, but none of them was specific to any one of the quinones tested. Mycelial extracts of P. chrysosporium contained several more quinone reductases, with isoelectric points of 4.4, 4.7, 5.0, 5.3, 5.5 and 6.6. Quinone reductase activity could be induced by adding vanillic acid or 2-methoxy-1,4-benzoquinone to the growth medium in nitrogen-limited cultures and in carbon-limited cultures.