title: Crystal and molecular structure of the bovine alpha-chymotrypsin-eglin c complex at 2.0 A resolution.
abstract: The crystal structure of the complex between bovine alpha-chymotrypsin and the leech (Hirudo medicinalis) protein proteinase inhibitor eglin c has been refined at 2.0 A resolution to a crystallographic R-factor of 0.167. The structure of the complex includes 2290 protein and 143 solvent atoms. Eglin c is bound to the cognate enzyme through interactions involving 11 residues of the inhibitor (sites P5-P4' in the reactive site loop, P10' and P23') and 17 residues from chymotrypsin. Binding of eglin c to the enzyme causes a contained hinge-bending movement around residues P4 and P4' of the inhibitor. The tertiary structure of chymotrypsin is little affected, with the exception of the 10-13 region, where an ordered structure for the polypeptide chain is observed. The overall binding mode is consistent with those found in other serine proteinase-protein-inhibitor complexes, including those from different inhibition families. Contained, but significant differences are observed in the establishment of intramolecular hydrogen bonds and polar interactions stabilizing the structure of the intact inhibitor, if the structure of eglin c in its complex with chymotrypsin is compared with that of other eglin c-serine proteinase complexes.
authors.affiliation: Dipartimento di Genetica e Microbiologia, Università di Pavia, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Frigerio
authors.forename: A
authors.initials: A
authors.lastname: Coda
authors.forename: L
authors.initials: L
authors.lastname: Pugliese
authors.forename: C
authors.initials: C
authors.lastname: Lionetti
authors.forename: E
authors.initials: E
authors.lastname: Menegatti
authors.forename: G
authors.initials: G
authors.lastname: Amiconi
authors.forename: H P
authors.initials: HP
authors.lastname: Schnebli
authors.forename: P
authors.initials: P
authors.lastname: Ascenzi
authors.forename: M
authors.initials: M
authors.lastname: Bolognesi
mesh_terms: D000818:Animals; D001665:Binding Sites; D002417:Cattle; D002918:Chymotrypsin / Q000737:chemistry* / Q000378:metabolism; D006860:Hydrogen Bonding; D008958:Models, Molecular; D011487:Protein Conformation; D011506:Proteins; D015842:Serine Proteinase Inhibitors / Q000737:chemistry* / Q000378:metabolism; D015843:Serpins; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: D011506:Proteins; D015842:Serine Proteinase Inhibitors; D015843:Serpins; C028656:eglin proteinase inhibitors; D002918:Chymotrypsin