小中大1.8. Sequence similarity suggests homology and possible cofactor affinity
If your protein is of unknown function, it is possible to do a search to determine if it is highly similar to other known proteins in the protein database. If the sequence similarity is great enough to infer homology and if your protein is related to other homologous family members that have been studied, then perhaps you know, for example, that it usually occurs as a. This will help in predicting its behavior on gel filtration column chromatography. This information might also be used to devise a suitable assay for your protein. Again, as above, sequence can identify if it belongs to a protein family all of which are known to bind to a particular cofactor or substrate. For example, if it is a member of the AAA ATPase family, it is likely that it will bind to an affinity column that has an immobilized ATP analog. Such an affinity purification step can aid greatly in a purification scheme (see Chapter 26).
序列相似意味着同源性和可能的辅助因子亲和性
如果目标蛋白功能未知,可以做一些搜索看看它是否与蛋白质数据库中的其它已知蛋白高度相似。如果序列相似性达到足以推断为同源,并且目标蛋白与其他已研究过的同源性家族蛋白相关,那么通常可以当着同(源)二聚体。这对凝胶过滤柱层析的行为预测很有帮助。这一信息也有可能用来设计一个针对目标蛋白的可行分析方法。如上所述,再次强调,特定的蛋白质家族都已知结合一种特殊的辅助因子或底物,序列分析可以验证目标蛋白是否属于这个蛋白质家族。举个例子,如果目标蛋白是AAA ATP酶家族的一员,很可能它就能吸附于ATP类似物配基的亲和层析柱。这样一种亲和纯化步骤对纯化流程来说帮助极大。
反复看了,同(源)二聚体homodimer这段看不懂。相似、同源可以理解,但与二聚体又有何干?二聚体当然与Gel Filtration有关,但同源扯不上吧?
亲和层析的设计这段不错。其实商品化的此类介质已经有很多了,如Blue,Heparin等。