PDBsum entry 1kgm

Hydrolase

PDB id: 1kgm

Contents

Protein chain

35 a.a.

PDB id:

1kgm

Name:

Hydrolase

Title:

Solution structure of the small serine protease inhibitor sgci

Structure:

Serine protease inhibitor i. Chain: a. Fragment: residues 57-91. Synonym: schistocerca gregaria chymotrypsin inhibitor (sgci). Engineered: yes

Source:

Synthetic: yes. Other_details: solid-phase synthesis, fmoc strategy, sequence naturally found in schistocerca gregaria (desert locust)

NMR struc:

10 models

Authors:

Z.Gaspari,A.Patthy,L.Graf,A.Perczel

Key ref:

Z.Gáspári et al. (2002). Comparative structure analysis of proteinase inhibitors from the desert locust, Schistocerca gregaria. Eur J Biochem, 269, 527-537. PubMed id: 11856311 DOI: 10.1046/j.0014-2956.2001.02685.x

Date:

28-Nov-01 Release date: 12-Dec-01

Protein chain

O46162  (SGP1_SCHGR) -  Serine protease inhibitor I/II from Schistocerca gregaria

Seq: 92 a.a.

Struc: 35 a.a.

DOI no: 10.1046/j.0014-2956.2001.02685.x

Eur J Biochem 269:527-537 (2002)

PubMed id: 11856311

Comparative structure analysis of proteinase inhibitors from the desert locust, Schistocerca gregaria.

Z.Gáspári, A.Patthy, L.Gráf, A.Perczel.

ABSTRACT

The solution structure of three small serine proteinase inhibitors, two natural and one engineered protein, SGCI (Schistocerca gregaria chymotrypsin inhibitor), SGCI[L30R, K31M] and SGTI (Schistocerca gregaria trypsin inhibitor), were determined by homonuclear NMR-spectroscopy. The molecules exhibit different specificities towards target proteinases, where SGCI is a good chymotrypsin inhibitor, its mutant is a potent trypsin inhibitor, and SGTI inhibits both proteinases weakly. Interestingly, SGTI is a much better inhibitor of insect proteinases than of the mammalian ones used in common assays. All three molecules have a similar fold composed from three antiparallel beta-pleated sheets with three disulfide bridges. The proteinase binding loop has a somewhat distinct geometry in all three peptides. Moreover, the stabilization of the structure is different in SGCI and SGTI. Proton-deuterium exchange experiments are indicative of a highly rigid core in SGTI but not in SGCI. We suggest that the observed structural properties play a significant role in the specificity of these inhibitors.

Selected figure(s)

Figure 3.
Fig. 3. Backbone of 10 superimposed structures of SGCI (A) and 10 superimposed structures of SGTI (B). Schematic representation of the secondary structure elements and the disulfide bonding pattern of SGCI (C) and SGTI (D). Residues giving sidechain NOEs to Phe10 in SGCI (E) and the Lys10–Trp25 interaction of SGTI (F). (A), (B), (E) and (F) were prepared with sybyl[19], (C) and (D) with molscript[38] and raster3d[39].

Figure 4.
Fig. 4. Comparison of the H -trace of the binding loop of SGCI (blue), PMP-C (red), the turkey ovomucoid third domain inhibitor [ 29 ] (green) and the Bowman-Birk inhibitor [ 30 ] (orange). Structures are superimposed between residues P3 and P3'. This figure was prepared with sybyl[19].

The above figures are reprinted by permission from the Federation of European Biochemical Societies: Eur J Biochem (2002, 269, 527-537) copyright 2002.

Figures were selected by an automated process.