Katz D S, Wei A, Zhong Q, Rubin H, Cooperman B S, Christianson D W
Department of Chemistry, University of Pennsylvania, Philadelphia 19104.
Biochem Biophys Res Commun. 1993 Oct 29;196(2):752-7. doi: 10.1006/bbrc.1993.2313.
Crystals of two recombinant antichymotrypsin (rACT) variants have been prepared: variant rACT-T345R crystallizes in space group P2(1) (a = 109.2 A, b = 79.4 A, c = 111.9 A, beta = 116.3 degrees, with 2 molecules in the asymmetric unit), and variant ACT' crystallizes in space group P2(1)22(1) (a = 69.7 A, b = 77.2 A, c = 83.8 A, with one molecule in the asymmetric unit). The latter variant is an engineered dimer having the P3-P3' hexapeptide sequence of the related serpin, alpha 1-proteinase inhibitor, substituted for the corresponding wild-type sequence. Crystals of each variant diffract to a limiting resolution of 2.5 A, which represents the best diffraction yet achieved for a crystalline, inhibitory serpin. The exceptional quality of ACT' crystals probably arises from favorable protein-protein interactions as well as a stabilizing disulfide crosslink engineered between the monomers.
已制备出两种重组抗胰凝乳蛋白酶（rACT）变体的晶体：变体rACT-T345R在空间群P2(1)中结晶（a = 109.2 Å，b = 79.4 Å，c = 111.9 Å，β = 116.3°，不对称单元中有2个分子），变体ACT'在空间群P2(1)22(1)中结晶（a = 69.7 Å，b = 77.2 Å，c = 83.8 Å，不对称单元中有1个分子）。后一种变体是一种工程化二聚体，其具有相关丝氨酸蛋白酶抑制剂α1-抗胰蛋白酶的P3-P3'六肽序列，取代了相应的野生型序列。每个变体的晶体衍射极限分辨率为2.5 Å，这是结晶抑制性丝氨酸蛋白酶抑制剂迄今所达到的最佳衍射效果。ACT'晶体的优异品质可能源于有利的蛋白质-蛋白质相互作用以及单体之间工程化的稳定二硫键交联。
