Characterization and crystallization of the helicase domain of bacteriophage T7 gene 4 protein.

Limited proteolysis of bacteriophage T7 primase/helicase with endoproteinase Glu-C produces several proteolytic fragments. One of these fragments, which is derived from the C-terminal region of the protein, was prepared and shown to retain helicase activity. This result supports a model in which the gene 4 proteins consist of functionally separable domains. Crystals of this C-terminal fragment of the protein have been obtained that are suitable for X-ray diffraction studies.采用Glu-C蛋白内切酶（endoproteinase Glu-C）对T7噬菌体引物酶/解旋酶（bacteriophage T7 primase/helicase）进行有限蛋白水解，可得到若干蛋白水解片段。其中一个源自该蛋白C端区域的片段已被制备获得，并被证实仍保留解旋酶活性。这一结果支持了“基因4蛋白由功能可分离的结构域组成”的模型。现已获得该蛋白C端片段的晶体，其适用于X射线衍射研究。