3psg
From Proteopedia
THE HIGH RESOLUTION CRYSTAL STRUCTURE OF PORCINE PEPSINOGEN
Overview
The structure of porcine pepsinogen at pH 6.1 has been refined to an R-factor of 0.173 for data extending to 1.65 A. The final model contains 180 solvent molecules and lacks density for residues 157-161. The structure of this aspartic proteinase zymogen possesses many of the characteristics of pepsin, the mature enzyme. The secondary structure of the zymogen consists predominantly of beta-sheet, with an approximate 2-fold axis of symmetry. The activation peptide packs into the active site cleft, and the N-terminus (1P-9P) occupies the position of the mature N-terminus (1-9). Thus changes upon activation include excision of the activation peptide and proper relocation of the mature N-terminus. The activation peptide or residues of the displaced mature N-terminus make specific interactions with the substrate binding subsites. The active site of pepsinogen is intact; thus the lack of activity of pepsinogen is not due to a deformation of the active site. Nine ion pairs in pepsinogen may be important in the advent of activation and involve the activation peptide or regions of the mature N-terminus which are relocated in the mature enzyme. The activation peptide-pepsin junction, 44P-1, is characterized by high thermal parameters and weak density, indicating a flexible structure which would be accessible to cleavage. Pepsinogen is an appropriate model for the structures of other zymogens in the aspartic proteinase family.
About this Structure
3PSG is a Single protein structure of sequence from Sus scrofa. This structure supersedes the now removed PDB entry 1psg. The following page contains interesting information on the relation of 3PSG with [Pepsin]. Full crystallographic information is available from OCA.
Reference
The high-resolution crystal structure of porcine pepsinogen., Hartsuck JA, Koelsch G, Remington SJ, Proteins. 1992 May;13(1):1-25. PMID:1594574 Page seeded by OCA on Sun May 4 22:11:10 2008
