title: Structure of the complex of trypsin with a highly potent synthetic inhibitor at 0.97 A resolution.
abstract: The structure of the complex formed between bovine beta-trypsin and the highly potent synthetic inhibitor 2-{3'-[5'-methoxy-2'-(N-p-diaminomethylphenyl)amido]-1'-pyrido}-5-(N-2''-t-butylethanol)amidobenzoic acid (C(28)H(32)N(5)O(6)) has been determined at 0.97 A resolution. X-ray intensity data were collected to 0.97 A under cryocooled conditions. The structure was refined anisotropically using REFMAC5 and SHELX-97 to R(cryst) factors of 13.4 and 12.6% and R(free) factors of 15.7 and 16.3%, respectively. Several regions of the main chain and side chains that have not been previously observed were clearly defined in the present structure. H atoms are indicated as significant peaks in an |F(o) - F(c)| difference map, which accounts for an estimated 35% of all H atoms at the 2.5sigma level. The C, N and O atoms are definitively differentiated in the electron-density maps. The amido part of the inhibitor occupies the specificity pocket and the remainder fills the remaining part of the ligand-binding cleft and interacts with the enzyme through an extensive network of hydrogen bonds. The inhibitor distorts the stereochemistry of the catalytic triad, Ser195-His57-Asp102, thereby blocking the proton-relay process of the active site by preventing the formation of the crucial hydrogen bond between His57 N(delta1) and Asp102 O(delta1).
authors: Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110029, India.
authors: Manashi
authors: M
authors: Sherawat
authors: Punit
authors: P
authors: Kaur
authors: Markus
authors: M
authors: Perbandt
authors: Christian
authors: C
authors: Betzel
authors: William A
authors: WA
authors: Slusarchyk
authors: Gregory S
authors: GS
authors: Bisacchi
authors: Chiehying
authors: C
authors: Chang
authors: Bruce L
authors: BL
authors: Jacobson
authors: Howard M
authors: HM
authors: Einspahr
authors: Tej P
authors: TP
authors: Singh
mesh_terms: D000818:Animals; D001665:Binding Sites; D002417:Cattle; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D008958:Models, Molecular; D011487:Protein Conformation; D017510:Protein Folding; D014357:Trypsin / Q000737:chemistry* / Q000378:metabolism; D014361:Trypsin Inhibitors / Q000737:chemistry* / Q000494:pharmacology
chemical_list: D014361:Trypsin Inhibitors; D014357:Trypsin