The Pi-Screens were developed at the MRC Laboratory of Molecular Biology (Cambridge, UK) for efficient crystallization screening of soluble proteins (Pi-minimal Screen) and integral membrane proteins (Pi-PEG Screen). The approach is based on incomplete factorial design.

The unique formulation was generated following a strategy named Pi sampling [1] in order to create novel combinations of precipitants, buffers and additives across a standard 96-condition plate layout. Thus, the diversity amongst the crystallization conditions is ideal for initial screening.

The Pi-minimal Screen includes 36 components, i.e. 12 precipitants, 12 buffers systems and 12 salts. Buffers employed in the Pi-minimal screen are buffer systems (acid-base pairs, e.g. HEPES and HEPES sodium salt). Consequently, pH can be adjusted by mixing 2 stock solutions at different ratios during later optimizations.
The efficiency of the Pi-minimal Screen was demonstrated by the crystallization of 10 proteins before its commercialization [1].

The Pi-PEG Screen includes various polyethylene glycol mixtures, additives and buffers covering a pH range from 4,0 – 9,5 and hence is suitable for integral membrane proteins as well as for soluble proteins.
The efficiency of the Pi-PEG screen was demonstrated by the crystallization of a G-protein coupled receptor (GPCR) when quality crystals could not be produced with other commercially available screens [1].

Format

Bulk – 4 x 24 screening solutions in 10 ml aliquots
HTS – 96 screening solutions delivered in a deep-well block, 1.7 ml per well

类别：结晶筛
产品信息
产品描述
规格 – 屏幕条件
Pi-Screens 是在 MRC 分子生物学实验室（英国剑桥）开发的，用于对可溶性蛋白质（Pi-minimal Screen）和整合膜蛋白（Pi-PEG Screen）进行有效的结晶筛选。该方法基于不完全因子设计。

独特的配方是按照名为 Pi 采样 [1] 的策略生成的，目的是在标准 96 条件板布局中创建沉淀剂、缓冲剂和添加剂的新组合。因此，结晶条件之间的多样性是初始筛选的理想选择。

Pi-minimal Screen 包括 36 种成分，即 12 种沉淀剂、12 种缓冲液系统和 12 种盐。 Pi-minimal 筛选中使用的缓冲液是缓冲系统（酸碱对，例如 HEPES 和 HEPES 钠盐）。因此，在以后的优化过程中，可以通过混合不同比例的 2 种原液来调整 pH 值。
Pi-minimal Screen 的效率通过 10 种蛋白质在其商业化之前的结晶得到证明 [1]。

Pi-PEG Screen 包括各种聚乙二醇混合物、添加剂和缓冲液，pH 范围为 4,0 – 9,5，因此适用于整合膜蛋白以及可溶性蛋白。
Pi-PEG 筛选的效率通过 G 蛋白偶联受体 (GPCR) 的结晶来证明，当使用其他市售筛选无法生产高质量晶体时 [1]。

格式

散装 – 4 x 24 筛选溶液，每 10 毫升等分试样
HTS – 96 种筛选溶液以深孔模块形式提供，每孔 1.7 ml

Selected Recent Literature Citations of Pi-Screens

• Gorrec (2016) Protein crystallization screens developed at the MRC Laboratory of Molecular Biology. Drug Discov. Today 21:819.
• Ohashi et al. (2016) Characterization of Atg38 and NRBF2, a fifth subunit of the autophagic Vps34/PIK3C3 complex. Autophagy12:2129.
• Omari et al. (2014) Pushing the limits of sulfur SAD phasing: de novo structure solution of the N-terminal domain of the ectodomain of HCV E1. Acta Cryst. D 70:2197