Proteome-pI : proteome isoelectric point database

Proteome-pI is an online database containing information about predicted isoelectric points for 5,029 proteomes (21 million of sequences) calculated using 18 methods. The isoelectric point, the pH at which a particular molecule carries no net electrical charge, is an important parameter for many analytical biochemistry and proteomics techniques, especially for 2D gel electrophoresis (2D-PAGE), capillary isoelectric focusing, liquid chromatography–mass spectrometry and X-ray protein crystallography. The database allows the retrieval of virtual 2D-PAGE plots and the development of customized fractions of proteome based on isoelectric point and molecular weight. Moreover, Proteome-pI facilitates statistical comparisons of the various prediction methods as well as biological investigation of protein isoelectric point space in all kingdoms of life (http://isoelectricpointdb.org/statistics.html). The database includes various statistics and tools for interactive browsing, searching and sorting. It can be searched and browsed by organism name, average isoelectric point, molecular weight or amino acid frequencies. Proteins with extreme pI values are also available. For individual proteomes, users can retrieve proteins of interest given the method, isoelectric point and molecular weight ranges (this particular feature can be highly useful to limit potential targets in analysis of 2DPAGE gels or before conducting mass spectrometry). Finally, some general statistics (total number of proteins, amino acids, average sequence length, amino acid and di-amino acid frequencies) and datasets corresponding to major protein databases such as UniProtKB/TrEMBL and the NCBI non-redundant (nr) database have also been precalculated.

Proteome-pI 是一个在线数据库，收录了通过18种计算方法预测得到的5029个蛋白质组（共计2100万条序列）的等电点（isoelectric point）相关信息。等电点是指特定分子净电荷为零时的pH值，是诸多分析生物化学与蛋白质组学技术的关键参数，尤其在二维凝胶电泳（2D-PAGE）、毛细管等电聚焦、液相色谱-质谱联用以及X射线蛋白质晶体学等实验技术中具有重要应用价值。该数据库支持虚拟二维凝胶电泳图谱的检索，同时可基于等电点与分子量实现定制化蛋白质组亚组分的生成与筛选。此外，Proteome-pI 可支持多种预测方法的统计对比分析，以及对生物所有分类界内蛋白质等电点分布空间的生物学研究（访问地址：http://isoelectricpointdb.org/statistics.html）。数据库集成了多种用于交互式浏览、检索与排序的统计工具与功能，支持通过生物名称、平均等电点、分子量或氨基酸频率进行检索与浏览，极端等电点值的蛋白质数据集同样可供获取。针对单个蛋白质组，用户可根据指定的预测方法、等电点范围与分子量范围检索目标蛋白质；该功能在二维凝胶电泳凝胶分析或质谱检测前筛选潜在靶标时具备极高的实用价值。此外，数据库还预先计算了多项通用统计指标，包括蛋白质总数量、氨基酸组成、平均序列长度、单氨基酸与二氨基酸频率，同时还提供了对应主流蛋白质数据库（如UniProtKB/TrEMBL与NCBI非冗余（non-redundant, nr）数据库）的预计算数据集。

搜集汇总

背景与挑战

背景概述

Proteome-pI是一个在线数据库，包含5029个蛋白质组（2100万条序列）的等电点预测信息，采用18种方法计算。等电点作为关键生化参数，支持2D凝胶电泳等分析技术，数据库提供虚拟2D-PAGE图、基于等电点和分子量的定制分析，并允许按生物体名称、平均等电点等条件进行搜索浏览和统计比较。