1sm7
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(New page: 200px<br /><applet load="1sm7" size="450" color="white" frame="true" align="right" spinBox="true" caption="1sm7" /> '''Solution structure of the recombinant pronap...)
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Revision as of 22:38, 24 November 2007
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Solution structure of the recombinant pronapin precursor, BnIb.
Overview
NMR spectroscopy has been used to determine the solution structure of the, precursor form of the recombinant napin BnIb, rproBnIb, a 2S albumin, 109-residue protein from the seeds of Brassica napus. More than 90% of the, side-chain proton resonances were unambiguously assigned from the analysis, of two-dimensional correlation (COSY), total correlation (TOCSY), and, nuclear Overhauser effect (NOESY) spectra. The final structures were, computed by using restrained molecular dynamics on the basis of 1316, upper-limit distance constraints derived from NOE cross-correlation, intensities. The computed structures exhibited a root-mean-square, deviation (RMSD) radius of 0.66 A for the backbone and 1.16 A for the, side-chain heavy atoms of the structural core. The resulting structure, consists of five amphipathic helices arranged in a right-handed super, helix, a folding motif found in other proteins of the prolamin, superfamily. As in the case of the mature protein, the recombinant, precursor behaves as a plant food allergen. To trace out the origin and, characteristics of its allergenic properties, rproBnIb was assayed against, simulated gastric fluid and found to be very resistant to proteolysis., Also, heat treatment of the protein followed up to 85 degrees C by, circular dichroism showed a very limited unfolding, which was recovered, after cooling to 20 degrees C, indicating a high thermal stability. These, results suggest that rproBnIb, as other 2S albumins, may be able to reach, the gut immune system intact. A comparison of the putative epitopes, against IgE antibodies of the three members of the prolamine family [2S, albumins, nonspecific lipid transfer proteins (nsLTPs), and, alpha-amylase/trypsin inhibitors] indicates that there are not common, surfaces of interaction with IgE. Though the epitopes appear to be located, in different regions of the proteins, they do comply with the requirements, of being solvent-exposed and flexible.
About this Structure
1SM7 is a Single protein structure of sequence from Brassica napus. Full crystallographic information is available from OCA.
Reference
Solution structure and stability against digestion of rproBnIb, a recombinant 2S albumin from rapeseed: relationship to its allergenic properties., Pantoja-Uceda D, Palomares O, Bruix M, Villalba M, Rodriguez R, Rico M, Santoro J, Biochemistry. 2004 Dec 28;43(51):16036-45. PMID:15609998
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