PDBsum entry 1bpi

Proteinase inhibitor (trypsin)

PDB id: 1bpi

Contents

Protein chain

58 a.a. *

Ligands

PO4

Waters ×167

* Residue conservation analysis

PDB id:

1bpi

Name:

Proteinase inhibitor (trypsin)

Title:

The structure of bovine pancreatic trypsin inhibitor at 125k: definition of carboxyl-terminal residues glycine-57 and alanine-58

Structure:

Bovine pancreatic trypsin inhibitor. Chain: a. Engineered: yes

Source:

Bos taurus. Cattle. Organism_taxid: 9913

Resolution:

1.09Å R-factor: 0.187

Authors:

S.Parkin,B.Rupp,H.Hope

Key ref:

S.Parkin et al. (1996). Structure of bovine pancreatic trypsin inhibitor at 125 K definition of carboxyl-terminal residues Gly57 and Ala58. Acta Crystallogr D Biol Crystallogr, 52, 18-29. PubMed id: 15299722 DOI: 10.1107/S0907444995008675

Date:

18-Feb-95 Release date: 03-Jun-95

Protein chain

P00974  (BPT1_BOVIN) -  Pancreatic trypsin inhibitor from Bos taurus

Seq: 100 a.a.

Struc: 58 a.a.

DOI no: 10.1107/S0907444995008675

Acta Crystallogr D Biol Crystallogr 52:18-29 (1996)

PubMed id: 15299722

Structure of bovine pancreatic trypsin inhibitor at 125 K definition of carboxyl-terminal residues Gly57 and Ala58.

S.Parkin, B.Rupp, H.Hope.

ABSTRACT

The structure of bovine pancreatic trypsin inhibitor has been refined to a resolution of 1.1 A against data collected at 125 K. The space group of the form II crystal is P2(1)2(1)2(1) with a = 75.39(3), b = 22.581(7), c = 28.606 (9) A (cf. a = 74.1, b = 23.4, c = 28.9 A at room temperature). The structure was refined by restrained least-squares minimization of summation operator w(F (o)(2)- F (c)(2))(2) with the SHELXL93 program. As the model improved, water molecules were included and exceptionally clear electron density was found for two residues, Gly57 and Ala58, that had been largely obscured at room temperature. The side chains of residues Glu7 and Arg53 were modelled over two positions with refined occupancy factors. The final model contains 145.6 water molecules distributed over 167 sites, and a single phosphate group disordered over two sites. The root-mean-square discrepancy between Calpha atoms in residues Arg1-Gly56 at room and low temperatures is 0.4 A. A comparison of models refined with anisotropic and isotropic thermal parameters revealed that there were no significant differences in atomic positions. The final weighted R-factor on F(2) (wR(2)) for data in the range 10-1.1 A was 35.9% for the anisotropic model and 40.9% for the isotropic model. Conventional R-factors based on F for F > 4sigma(F) were 12.2 and 14.6%, respectively, corresponding to 16.1 and 18.7% on all data. These large R-factor differences were not reflected in values of R(free), which were not significantly different at 21.5(5) and 21.8(4)%, respectively. These results, along with the relatively straightforward nature of the refinement, clearly highlight the benefits of low-temperature data collection.

Selected figure(s)

Figure 4.
Fig. 4. Electron densities contoured at i.0~ and 0.5a (coefficients Fobs) at the tw residues (a) Glu7 and (b) Arg53 for which refined disorder models were included.

Figure 7.
Fig. 7. Electron densities contoured at la, 3a and 5a (coefficients Fobs.) in regions with high refined thermal parameters at 125 K, the side chains of residues (a) Asp3, (b) Lysl5, (c) Arg39 and (d) Arg42.

The above figures are reprinted by permission from the IUCr: Acta Crystallogr D Biol Crystallogr (1996, 52, 18-29) copyright 1996.

Figures were selected by an automated process.