Schmidt-Krey Ingeborg, Haase Winfried, Mutucumarana Vasantha, Stafford Darrel W, Kühlbrandt Werner
Georgia Institute of Technology, School of Biology, 310 Ferst Drive, Atlanta, GA 30332-0230, USA.
J Struct Biol. 2007 Feb;157(2):437-42. doi: 10.1016/j.jsb.2006.08.002. Epub 2006 Aug 15.
Planar-tubular two-dimensional (2D) crystals of human vitamin K-dependent gamma-glutamyl carboxylase grow in the presence of dimyristoyl phosphatidylcholine (DMPC). Surprisingly, these crystals form below the phase transition temperature of DMPC and at the unusually low molar lipid-to-protein (LPR) ratio of 1, while 2D crystals are conventionally grown above the phase transition temperature of the reconstituting lipid and significantly higher LPRs. The crystals are up to 0.75 microm in the shorter dimension of the planar tubes and at least 1 microm in length. Due to the planar-tubular nature of the crystals, two lattices are present. These are rotated by nearly 90 degrees in respect to each other. The ordered arrays exhibit p12(1) plane group symmetry with unit cell dimensions of a=83.7 A, b=76.6 A, gamma=91 degrees. Projection maps calculated from images of negatively stained and electron cryo-microscopy samples reveal the human vitamin K-dependent gamma-glutamyl carboxylase to be a monomer.
人维生素K依赖性γ-谷氨酰羧化酶的平面管状二维（2D）晶体在二肉豆蔻酰磷脂酰胆碱（DMPC）存在下生长。令人惊讶的是，这些晶体在DMPC的相变温度以下且在异常低的1的摩尔脂质与蛋白质（LPR）比下形成，而传统上2D晶体是在重构脂质的相变温度以上且在显著更高的LPR下生长。晶体在平面管较短维度上可达0.75微米，长度至少为1微米。由于晶体的平面管状性质，存在两种晶格。它们彼此相对旋转近90度。有序阵列呈现p12(1)平面群对称性，晶胞尺寸为a = 83.7 Å，b = 76.6 Å，γ = 91度。从负染和电子冷冻显微镜样品图像计算得到的投影图显示人维生素K依赖性γ-谷氨酰羧化酶是单体。
