본 연구는 옻나무의 allergy유발성분으로 알려진 urushiol이 장수버섯(Fomitella fraxinea)의 laccase유도에 미치는 영향을 살펴보고 laccase isoenzyme을 분리 정제하여 그 특성을 살펴보았다. 장수버섯의 laccase활성과 균체생산량은 배양 10일째 최대치를 나타내었으며 urushiol첨가에 의해서 효소활성은 2.45배, 균체량은 1.5배 높아졌다. Laccase생산용 배지에서 Cu와 Mn이온을 결핍시켰을 경우 효소활성은 3.8-9.2배 낮아졌으나 균체생산에는 영향이 비교적 적었다. Anion exchange, hydrophobic interaction 및 gel filtration chromatography를 통하여 2종의 laccase isoenzyme(Lac1, Lac2)을 정제하였다. 이 효소는 단량체로 각각 67 kDa(Lac1)과 66 kDa(Lac2)의 분자량을 가지고 있었으며, 등전점은 3.67과 3.81이었다. 두 효소 모두 pH 4.5-5.0, $30-35^{circ}C$에서 최대 활성을 보였으며, $Fe^{2+}$, $Mg^{2+}$, $Na^+$에 의해서 저해를 받았다. 또한, EDTA와 sodium azide에 의해서도 효소활성이 강하게 저해 받았다.
The influence of urushiol, as an allergen on laccase property of Fomitella fraxinea was investigated. The enzyme production was reached to the highest level after 10 days, cultivation and the activity and mycelial biomass were increased by 2.5 and 1.5 folds, respectively, by adding urushiol in the culture medium. In liquid cultures using a Cu Mn-free medium, laccase lactivity was decreased by 3.8-9.2 folds, with similar dry cell weight. Two isoenzymes, were purified using anion exchange, hydrophobic interaction and size-exclusion chromatographies. Both isoenzymes are monomeric proteins, with $M_W$ around 67 kDa(Lac1) and 66 kDa(Lac2), and isoelectric points of 3.67 and 3.81. The optimal conditions for purified isoenzymes were found to be pH 4.5-5.0 and $30-35^{circ}C$. Activity decreased by the addition of $Fe^{2+}$, $Mg^{2+}$, $Na^+$, and strongly inhibited by EDTA and sodium azide.
