1mvz
NMR solution structure of a Bowman Birk inhibitor isolated from snail medic seeds (Medicago Scutellata)
Structural highlights
FunctionIBB_MEDSC Inhibits trypsin but not chymotrypsin. Inhibits the trypsin-like proteinase activity present in larvae of the crop pests Adoxophyes orana, Hyphantria cunea, Lobesia botrana and Ostrinia nubilalis.[1] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe high-resolution three-dimensional structure of a Bowman Birk inhibitor, purified from snail medic seeds (Medicago scutellata) (MSTI), has been determined in solution by 1H NMR spectroscopy at pH 5.6 and 27 degrees C. The structure of MSTI comprises two distinct symmetric domains each composed of a three-stranded beta-sheet containing a VIb type loop, where the active sites are located. A characteristic geometry of three aromatic residues confers stability to this protein, and we observe that this feature is conserved in all the Bowman Birk inhibitors of known structure. The two active domains exhibit different conformational features: the second domain displays higher flexibility and hydrophobicity with respect to the first one, and these properties have been correlated to a lower trypsin inhibitory specificity, in agreement with titration studies that have shown a stoichiometric ratio MSTI:trypsin of 1:1.5. NMR analysis indicated that MSTI undergoes self-association at concentrations higher than 2 mM, and the residues involved in this mechanism are localized at opposite faces of the molecule, having the highest positive and negative potential, respectively, thus indicating that electrostatic intermolecular interactions are the driving forces for MSTI association. Most of the residues affected by self-association are highly conserved in BBIs from different seeds, suggesting a functional relevance for these charged superficial patches, possibly involved in the interaction with other enzymes or macromolecules, thus triggering anti-carcinogenic activity. Anticarcinogenic Bowman Birk inhibitor isolated from snail medic seeds (Medicago scutellata): solution structure and analysis of self-association behavior.,Catalano M, Ragona L, Molinari H, Tava A, Zetta L Biochemistry. 2003 Mar 18;42(10):2836-46. PMID:12627949[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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