THE REFINED 2.2-ANGSTROMS (0.22-NM) X-RAY CRYSTAL STRUCTURE OF THE TERNARY COMPLEX FORMED BY BOVINE TRYPSINOGEN, VALINE-VALINE AND THE ARG15 ANALOGUE OF BOVINE PANCREATIC TRYPSIN INHIBITOR
The refined 2.2-A (0.22-nm) X-ray crystal structure of the ternary complex formed by bovine trypsinogen, valine-valine and the Arg15 analogue of bovine pancreatic trypsin inhibitor
Large orthorhombic crystals of the complex formed by bovine trypsinogen and a semisynthetic homologous bovine pancreatic trypsin inhibitor with the reactive-site lysine residue replaced by an arginine residue [( Arg15]PTI) have been obtained which are isomorphous with the crystals of PTI-trypsinogen [Bode, W ...
Large orthorhombic crystals of the complex formed by bovine trypsinogen and a semisynthetic homologous bovine pancreatic trypsin inhibitor with the reactive-site lysine residue replaced by an arginine residue [( Arg15]PTI) have been obtained which are isomorphous with the crystals of PTI-trypsinogen [Bode, W., Schwager, P. and Huber, R. (1978) J. Mol. Biol. 118, 99-112]. The X-ray crystal structure of the ternary complex of trypsinogen-[Arg15]PTI with the dipeptide Val-Val has been determined by X-ray data to 2.2-A (0.22-nm) resolution by means of difference Fourier methods and has been crystallographically refined to a final R-value of 0.17. Replacement of the reactive-site Lys15 by an arginine residue is accompanied in the complex by small movements of polar side groups of trypsin and enclosed solvent molecules within the specificity pocket. Only solvent molecule 414 OH which mediates the hydrogen bond interactions between Lys15 NZ and Asp189 carboxylate is expelled, thus allowing the bulkier guanidyl group to approach this carboxylate. The dipeptide Val-Val binds in the pocket accepting the Ile-Val N-terminus in trypsin. The cavity left by the CD-methyl group of Ile16 upon replacement by a valine residue is only partially filled by slight rearrangements of neighbouring peptide side chains. Part of the positive free energy change observed upon replacement of Ile-Val may allow for the maintenance of this cavity.
Related Citations:
The Transition of Bovine Trypsinogen to a Trypsin-Like State Upon Strong Ligand Binding. II. The Binding of the Pancreatic Trypsin Inhibitor and of Isoleucine-Valine and of Sequentially Related Peptides to Trypsinogen and to P-Guanidinobenzoate-Trypsinogen Bode, W. (1979) J Mol Biol 127: 357
The Transition of Bovine Trypsinogen to a Trypsin-Like State Upon Strong Ligand Binding. The Refined Crystal Structures of the Bovine Trypsinogen-Pancreatic Trypsin Inhibitor Complex and of its Ternary Complex with Ile-Val at 1.9 Angstroms Resolution Bode, W., Schwager, P., Huber, R. (1978) J Mol Biol 118: 99
Organizational Affiliation:
Department of Cell Biology, La Jolla Institute for Allergy and Immunology, La Jolla CA 92037, USA.
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