Hakulinen Nina, Kiiskinen Laura-Leena, Kruus Kristiina, Saloheimo Markku, Paananen Arja, Koivula Anu, Rouvinen Juha
Department of Chemistry, University of Joensuu, PO BOX 111, FIN-80101, Joensuu, Finland.
Nat Struct Biol. 2002 Aug;9(8):601-5. doi: 10.1038/nsb823.
We have crystallized the ascomycete laccase from Melanocarpus albomyces with all four coppers present and determined the crystal structure at 2.4 A resolution. The enzyme is heavily glycosylated and consists of three cupredoxin-like domains, similar to those found in the Cu-depleted basidiomycete laccase from Coprinus cinereus. However, there are significant differences in the loops forming the substrate-binding pocket. In addition, the crystal structure of the M. albomyces laccase revealed elongated electron density between all three coppers in the trinuclear copper site, suggesting that an oxygen molecule binds with a novel geometry. This oxygen, required in the reaction, may enter the trinuclear site through the tunnel, which is open in the structure of the C. cinereus laccase. In contrast, the C-terminus on the M. albomyces laccase forms a plug that blocks this access.
我们已使来自白腐皮壳菌的子囊菌漆酶结晶，其中所有四个铜原子均存在，并在2.4埃分辨率下确定了晶体结构。该酶高度糖基化，由三个类铜蓝蛋白结构域组成，类似于在来自灰盖鬼伞的铜耗尽担子菌漆酶中发现的结构域。然而，形成底物结合口袋的环存在显著差异。此外，白腐皮壳菌漆酶的晶体结构显示，三核铜位点中所有三个铜原子之间存在拉长的电子密度，这表明一个氧分子以一种新的几何构型结合。反应中所需的这种氧可能通过隧道进入三核位点，该隧道在灰盖鬼伞漆酶的结构中是开放的。相比之下，白腐皮壳菌漆酶的C末端形成一个塞子，阻断了这种进入。
