The determination of the three-dimensional structure of barley serine proteinase inhibitor 2 by nuclear magnetic resonance, distance geometry and restrained molecular dynamics

Abstract

The solution structure of the 64 residue structured domain (residues 20-83) of barley serine proteinase inhibitor 2 (BSPI-2) is determined on the basis of 403 interproton distance, 34 phi backbone torsion angle and 26 hydrogen bonding restraints derived from n.m.r. measurements. A total of 11 converged structures were computed using a metric matrix distance geometry algorithm and refined by restrained molecular dynamics. The average rms difference between the final 11 structures and the mean structure obtained by averaging their coordinates is 1.4 +/- 0.2 A for the backbone atoms and 2.1 +/- 0.1 A for all atoms. The overall structure, which is almost identical to that found by X-ray crystallography, is disc shaped and consists of a central four component mixed parallel and antiparallel beta-sheet flanked by a 13 residue alpha-helix on one side and the reactive site loop on the other.

Secondary structure of barley serine proteinase inhibitor 2 determined by proton nuclear magnetic resonance spectroscopy

“…All of the secondary structure elements that were indicated by the NMR-data are seen in the X-ray structure and the hydrogen bonds proposed in this work are plausible from the X-ray coordinates of the relevant nitrogen and oxygen positions. In our NMR studies of the BSPI-2 we have determined the three-dimensional structure using a combination of distance geometry and restrained molecular dynamics (4,5). This structure also confirms the secondary structure elements outlined in the present study.…”

Crystal structure of a dimeric chymotrypsin inhibitor 2 mutant containing an inserted glutamine repeat

“…The pseudomonomers must therefore be related by a dyad axis of symmetry. All of the secondary structure elements (an ␣-helix and a four-stranded mixed parallel and antiparallel ␤-sheet) and the overall fold of the wild type are preserved (8,22). In both wild-type CI2 and CI2-Q4i, the proteins are arranged in layers FIG.…”

NMR solution structure of Apis mellifera chymotrypsin/cathepsin G inhibitor‐1 (AMCI‐1): Structural similarity with Ascaris protease inhibitors

“…Solution structures have been reported for typical representatives of many inhibitor families: bovine pancreatic trypsin inhibitor~BPTI family!~Berndt et al, 1992! ; barley seed chymotrypsin inhibitor 2 Clore et al, 1987!, andeglin c~Hyberts et al, 1992 The larval hemolymph of the honey bee~Apis mellifera! shows a high level of antiproteolytic activity against several serine proteases of different specificities~Polanowski et al, 1992!.…”