title: Isolation of a lectin binding rhamnogalacturonan-I containing pectic polysaccharide from pumpkin.
abstract: A rhamnogalacturonan-I (RG-I) containing pectic polysaccharide (PPc) was isolated from pumpkin following a low-temperature alkali treatment and a combination of gradual alcohol precipitation and ion-exchange. Monosaccharide compositional analysis of PPc revealed the presence of rhamnose, galacturonic acid, galactose, and arabinose in a molar ratio of 7.4: 25: 28: 2.6. Structural and linkage analysis by 1D NMR (1H NMR and13C NMR), and 2D NMR (COSY, TOCSY, HSQC, and elevated temperature HMBC) suggested that PPc was a RG-I-like pectic polysaccharide, branched at the C-4 of some of the (about 29% of) rhamnosyl units, with relatively long β-1,4-d-galactan side chains to which were attached, through the C-3 of β-d-Gal, terminal non reducing α-Araf units. The results of surface plasmon resonance (SPR) show that PPc binds to two types of lectin, Ricinus communis agglutinin 120 (RCA120) and Galectin-3 (Gal-3). These binding studies show quick association and slow dissociation with a moderate binding affinity between PPc and Gal-3 of 1.26μM. The interaction between PPc and Gal-3 suggest the potential use of pumpkin pectic polysaccharide as a Gal-3 inhibitor in functional food or drug development applications.
authors.affiliation: College of Food Science & Nutritional Engineering, China Agricultural University, Beijing, 100083, China; China National Engineering Research Center for Fruit and Vegetable Processing, Beijing 100083, China; Key Laboratory of Fruit and Vegetable Processing, Ministry of Agriculture, Beijing 100083, China; Department of Chemistry and Chemical Biology, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180, USA.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhao
authors.affiliation: Department of Chemical and Biological Engineering, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180, USA.
authors.forename: Fuming
authors.initials: F
authors.lastname: Zhang
authors.affiliation: Department of Chemistry and Chemical Biology, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180, USA.
authors.forename: Xinyue
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Chemistry and Chemical Biology, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180, USA.
authors.forename: Kalib
authors.initials: K
authors.lastname: St Ange
authors.affiliation: Department of Chemistry and Chemical Biology, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180, USA.
authors.forename: Anqiang
authors.initials: A
authors.lastname: Zhang
authors.affiliation: College of Food Science & Nutritional Engineering, China Agricultural University, Beijing, 100083, China; China National Engineering Research Center for Fruit and Vegetable Processing, Beijing 100083, China; Key Laboratory of Fruit and Vegetable Processing, Ministry of Agriculture, Beijing 100083, China. Electronic address: quanhong_li@hotmail.com.
authors.forename: Quanhong
authors.initials: Q
authors.lastname: Li
authors.affiliation: Department of Chemistry and Chemical Biology, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180, USA; Department of Chemical and Biological Engineering, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180, USA; Departments of Biology and Biomedical Engineering, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180, USA. Electronic address: linhar@rpi.edu.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Linhardt
mesh_terms: D028464:Cucurbita / Q000737:chemistry*; D005685:Galactans; D009682:Magnetic Resonance Spectroscopy; D009005:Monosaccharides; D010368:Pectins / Q000737:chemistry* / Q000302:isolation & purification; D011134:Polysaccharides / Q000737:chemistry*
chemical_list: D005685:Galactans; D009005:Monosaccharides; D011134:Polysaccharides; D010368:Pectins
keywords: Lectin; NMR; Pectin; Pumpkin residues; Rhamnogalacturonan-I