THE REFINED STRUCTURE OF THE QUINOPROTEIN METHANOL DEHYDROGENASE FROM METHYLOBACTERIUM-EXTORQUENS AT 1.94 ANGSTROM
THE REFINED STRUCTURE OF THE QUINOPROTEIN METHANOL DEHYDROGENASE FROM METHYLOBACTERIUM-EXTORQUENS AT 1.94 ANGSTROM
复制标题
DOI：
10.1016/s0969-2126(01)00148-4
复制
发表时间：
1995-02-15
期刊：
影响因子：
5.7
通讯作者：
BLAKE, C
中科院分区：
文献类型：
--
作者：
GHOSH, M;ANTHONY, C;BLAKE, C
背景资料：甲醇脱氢酶（methanol dehydrogenase，MDH）是一种细菌周质醌蛋白，以吡咯并喹啉醌（PQQ）为辅基，需要Ca 2+才能发挥活性，并以细胞色素c（cytochrome c，L）为电子受体。MDH的低分辨率结构已经被确定。结果：来自扭脱甲基杆菌的MDH的α（2）β（2）四聚体的结构现在已经在1.94埃处被确定，R因子为19.85%。MDH的α亚基具有八重径向对称性，它的8个beta-活性位点中的PQQ通过共面色氨酸和在相邻的半胱氨酸之间形成的新的二硫环保持在适当的位置，所述半胱氨酸通过一种不寻常的非平面反式肽键PQQ的羰基氧之一与Ca 2+结合，可能促进对底物的攻击，而另一个羰基氧在环的平面外，证实存在预测的自由基半醌形式的辅基。
Background: Methanol dehydrogenase (MDH) is a bacterial periplasmic quinoprotein; it has pyrrolo-quinoline quinone (PQQ) as its prosthetic group, requires Ca2+ for activity and uses cytochrome c(L) as its electron acceptor. Low-resolution structures of MDH have already been determined.Results: The structure of the alpha(2) beta(2) tetramer of MDH from Methylobacterium extorquens has now been determined at 1.94 Angstrom with an R-factor of 19.85%.Conclusions: The alpha-subunit of MDH has an eight-fold radial symmetry, with its eight beta-sheets stabilized by a novel tryptophan docking motif The PQQ in the active site is held in place by a coplanar tryptophan and by a novel disulphide ring formed between adjacent cysteines which are bonded by an unusual non-planar trans peptide bond. One of the carbonyl oxygens of PQQ is bonded to the Ca2+, probably facilitating attack on the substrate, and the other carbonyl oxygen is out of the plane of the ring, confirming the presence of the predicted free-radical semiquinone form of the prosthetic group.