Gallego del Sol Francisca, Ramón-Maiques Santiago, Santos Claudia F, Grangeiro Thalles B, Nagano Celso S, Farias Creuza M S A, Cavada Benildo S, Calvete Juan J
Instituto de Biomedicina de Valencia, CSIC, Jaime Roig 11, E-46010 Valencia, Spain.
Acta Crystallogr D Biol Crystallogr. 2002 Jan;58(Pt 1):167-9. doi: 10.1107/s0907444901018236. Epub 2001 Dec 21.
The crystallization and preliminary X-ray diffraction analysis of the seed lectin of Parkia platycephala, a Mimosoideae, regarded as the most primitive group of the Leguminosae plants, are reported. Its amino-acid sequence consists of three tandemly arranged jacalin-related beta-prism domains, which is a novel fold for a leguminous lectin. Furthermore, no other lectin structure with this arrangement of domains has been described. P2(1)2(1)2(1) crystals (unit-cell parameters a = 63.6, b = 68.5, c = 208.5 A), which diffract to a maximum resolution of 2.2 A, were obtained in hanging drops at pH 8 and 293 K by the vapor-diffusion method using 10% 2-propanol and 20% polyethylene glycol 4000 as precipitants. The asymmetric unit contains two lectin molecules and has a solvent content of 46%. Only a single beta-prism domain could be located by molecular replacement using the structure of the Helianthus tuberosus lectin (PDB code 1c3k) as the search model. Isomorphous heavy-atom derivatives are currently being produced to solve the complete structure of the P. platycephala seed lectin.
据报道，对被认为是豆科植物中最原始类群的含羞草科阔头球花豆种子凝集素进行了结晶及初步X射线衍射分析。其氨基酸序列由三个串联排列的与jacalin相关的β棱柱结构域组成，这对于豆科凝集素来说是一种新颖的折叠形式。此外，尚未描述过具有这种结构域排列的其他凝集素结构。通过气相扩散法，以10%异丙醇和20%聚乙二醇4000作为沉淀剂，在pH 8和293 K的悬滴中获得了P2(1)2(1)2(1)晶体（晶胞参数a = 63.6，b = 68.5，c = 208.5 Å），其衍射最高分辨率为2.2 Å。不对称单元包含两个凝集素分子，溶剂含量为46%。以菊芋凝集素的结构（PDB代码1c3k）作为搜索模型，通过分子置换仅定位到了一个β棱柱结构域。目前正在制备同晶型重原子衍生物以解析阔头球花豆种子凝集素的完整结构。
