Purification and partial characterization of a novel lectin from Dioclea lasiocarpa Mart seeds with vasodilator effects

A lectin from seeds of Dioclea lasiocarpa (DLL) was purified in a single step by affinity chromatography in a Sephadex G-50 column. DLL haemagglutinated rabbit erythrocytes showing stability even after 1?h of exposure to a different pH values (optimal between pH 6.0 and 8.0) but was inhibited after incubation with d-mannose and d-glucose. The pure protein possessed a molecular weight of 25?kDa by sodium dodecyl sulfate polyacrylamide gel electrophoresis and 25,410Da by mass spectrometry. The results analyzed by the software SELCON 3 indicate that beta-sheet secondary structures are predominant in DLL (approximately 40.2% antiparallel beta-sheet, 4.6% parallel beta-sheet, 7.2% alpha-helices, 17.3% turns, and 28.7% unordered structures). Mechanical activity of isolated aorta from rat measured by cumulative concentration curves of DLL, performed at the contraction plateau induced by phenylephrine in either endothelium-intact or denuded aorta. DLL (IC50?=?34.12?+/-?3.46?mu g/ml) relaxed precontracted endothelized aortic rings by 34.61?+/-?9.06%, 55.19?+/-?11.9%, and 81.33?+/-?14.35%, respectively, at 10?mu g/ml (initial concentration), 30?mu g/ml, and 100?mu g/ml (maximum effect). All effects occurred via interaction with lectin domains and participation of nitric oxide. Copyright (c) 2012 John Wiley & Sons, Ltd.