| Abstract
| - A detailed analysis of the secondary structure has been carried out on the polygalacturonase-inhibiting protein (PGIP) from Phaseolus vulgaris, a leucine-rich repeat (LRR) protein present in the cellwall of many plants. Far-UV CD and infrared spectroscopies coupled to constrained secondary structureprediction methods indicated the presence of 12 α- and 12 β-segments, thus allowing a schematicrepresentation of three domains of the protein, namely, the central LRR region and the two cysteine-richflanking domains. Peptides from endoproteinase-degraded PGIP were analyzed by mass spectrometry,and four disulfide bonds were identified. Mass spectrometric analysis in combination with glycosidasetreatments revealed two N-linked oligosaccharides located on Asn 64 and Asn 141. The main structureresembled the typical complex plant N-glycan consisting of a core pentasaccharide β1,2-xylosylated,carrying an α1,3-fucose linked to the innermost N-acetylglucosamine and one outer arm N-acetylglucosamine residue. The schematic representation of PGIP structural domains is discussed in the frameworkof the structure and function of LRR proteins.
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