title: Crystallization and atomic resolution X-ray diffraction analysis of antichymotrypsin variants.
abstract: 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.
authors.affiliation: Department of Chemistry, University of Pennsylvania, Philadelphia 19104.
authors.forename: D S
authors.initials: DS
authors.lastname: Katz
authors.forename: A
authors.initials: A
authors.lastname: Wei
authors.forename: Q
authors.initials: Q
authors.lastname: Zhong
authors.forename: H
authors.initials: H
authors.lastname: Rubin
authors.forename: B S
authors.initials: BS
authors.lastname: Cooperman
authors.forename: D W
authors.initials: DW
authors.lastname: Christianson
mesh_terms: D002918:Chymotrypsin / Q000037:antagonists & inhibitors; D003460:Crystallization; D015202:Protein Engineering; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry; D015843:Serpins / Q000737:chemistry*; D014961:X-Ray Diffraction / Q000379:methods
chemical_list: D011994:Recombinant Proteins; D015843:Serpins; D002918:Chymotrypsin