PDBsum entry 1c2a

Hydrolase inhibitor

PDB id: 1c2a

Contents

Protein chain

120 a.a. *

Waters ×41

* Residue conservation analysis

PDB id:

1c2a

Name:

Hydrolase inhibitor

Title:

Crystal structure of barley bbi

Structure:

Bowman-birk trypsin inhibitor. Chain: a

Source:

Hordeum vulgare. Organism_taxid: 4513

Resolution:

1.90Å R-factor: 0.191 R-free: 0.219

Authors:

H.K.Song,Y.S.Kim,J.K.Yang,J.Moon,J.Y.Lee,S.W.Suh

Key ref:

H.K.Song et al. (1999). Crystal structure of a 16 kDa double-headed Bowman-Birk trypsin inhibitor from barley seeds at 1.9 A resolution. J Mol Biol, 293, 1133-1144. PubMed id: 10547291 DOI: 10.1006/jmbi.1999.3239

Date:

23-Jul-99 Release date: 29-Dec-99

Protein chain

P12940  (IBB_HORVU) -  Bowman-Birk type trypsin inhibitor from Hordeum vulgare

Seq: 124 a.a.

Struc: 120 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

DOI no: 10.1006/jmbi.1999.3239

J Mol Biol 293:1133-1144 (1999)

PubMed id: 10547291

Crystal structure of a 16 kDa double-headed Bowman-Birk trypsin inhibitor from barley seeds at 1.9 A resolution.

H.K.Song, Y.S.Kim, J.K.Yang, J.Moon, J.Y.Lee, S.W.Suh.

ABSTRACT

The Bowman-Birk trypsin inhibitor from barley seeds (BBBI) consists of 125 amino acid residues with two inhibitory loops. Its crystal structure in the free state has been determined by the multiwavelength anomalous diffraction (MAD) method and has been refined to a crystallographic R-value of 19.1 % for 8.0-1.9 A data. This is the first report on the structure of a 16 kDa double-headed Bowman-Birk inhibitor (BBI) from monocotyledonous plants and provides the highest resolution picture of a BBI to date. The BBBI structure consists of 11 beta-strands and the loops connecting these beta-strands but it lacks alpha-helices. BBBI folds into two compact domains of similar tertiary structure. Each domain shares the same overall fold with 8 kDa dicotyledonous BBIs. The five disulfide bridges in each domain are a subset of the seven disulfide bridges in 8 kDa dicotyledonous BBIs. Two buried water molecules form hydrogen bonds to backbone atoms in the core of each domain. One interesting feature of this two-domain inhibitor structure is that the two P1 residues (Arg17 and Arg76) are approximately 40 A apart, allowing the two reactive-site loops to bind to and to inhibit two trypsin molecules simultaneously and independently. The conformations of the reactive-site loops of BBBI are highly similar to those of other substrate-like inhibitors. This structure provides the framework for modeling of the 1:2 complex between BBBI and trypsin.

Selected figure(s)

Figure 6.
Figure 6. Stereo diagram showing the interactions between two buried water molecules and surrounding backbone atoms. (a) The N domain; (b) the C domain. The distances between the water molecule and its hydrogen bonding atoms of the inhibitor are given.

Figure 8.
Figure 8. A hypothetical model for the 1:2 complex between BBBI and two trypsin molecules. (a) The back- bone model of BBBI (green tubes) and the electrostatic potential surface of trypsin molecules. (b) The backbone model of trypsins (magenta tubes) and the electrostatic potential surface of BBBI. The view in (b) is obtained by a 180 ° rotation of (a) around a horizontal axis. Posi- tively charged regions are blue and negatively charged regions are red. The N and C-terminal and P1 residues in BBBI and the catalytic triad (Asp102-His57-Ser195) in trypsin are labeled. This Figure was generated using GRASP (Nicholls, 1992).

The above figures are reprinted by permission from Elsevier: J Mol Biol (1999, 293, 1133-1144) copyright 1999.

Figures were selected by an automated process.