title: Crystal structure of cleaved human alpha 1-antichymotrypsin at 2.7 A resolution and its comparison with other serpins.
abstract: The crystal structure of proteolytically modified human alpha 1-antichymotrypsin (ACT), a member of the serpin superfamily, has been solved by Paterson search techniques and refined to an R-factor of 18.0% at 2.7 A resolution with mean deviations from standard bond lengths and angles of 0.013 A and 3.1 degrees, respectively. The final model consists of 374 amino acid residues, 126 solvent molecules and five sugar residues. Asn70 could be identified unambiguously as a glycosylation site and Asn104 is probably also glycosylated. The structure of cleaved ACT is compared with cleaved alpha 1-antitrypsin (alpha 1 PI) and with plakalbumin, which are prototypical models for cleaved and intact serpins, respectively. Cleaved ACT is very similar to cleaved alpha 1 PI; in particular, it has strand s4A, which is liberated by proteolysis, inserted as the middle strand in beta-sheet A. ACT and alpha 1 PI differ locally only at sites of insertions, except at the segment s3C-turn-s4C, which is displaced by several angström units. This region of ACT is involved in DNA binding.
authors.affiliation: Max-Planck-Institut für Biochemie, Martinsried, Germany.
authors.forename: U
authors.initials: U
authors.lastname: Baumann
authors.forename: R
authors.initials: R
authors.lastname: Huber
authors.forename: W
authors.initials: W
authors.lastname: Bode
authors.forename: D
authors.initials: D
authors.lastname: Grosse
authors.forename: M
authors.initials: M
authors.lastname: Lesjak
authors.forename: C B
authors.initials: CB
authors.lastname: Laurell
mesh_terms: D000595:Amino Acid Sequence; D002240:Carbohydrate Sequence; D002241:Carbohydrates / Q000737:chemistry; D006031:Glycosylation; D006801:Humans; D006860:Hydrogen Bonding; D008969:Molecular Sequence Data; D010047:Ovalbumin / Q000737:chemistry* / Q000378:metabolism; D010446:Peptide Fragments / Q000737:chemistry* / Q000378:metabolism; D011487:Protein Conformation; D016415:Sequence Alignment; D014961:X-Ray Diffraction; D000514:alpha 1-Antichymotrypsin / Q000737:chemistry* / Q000378:metabolism; D000515:alpha 1-Antitrypsin / Q000737:chemistry* / Q000378:metabolism
chemical_list: D002241:Carbohydrates; D010446:Peptide Fragments; D000514:alpha 1-Antichymotrypsin; D000515:alpha 1-Antitrypsin; C038141:plakalbumin; D010047:Ovalbumin