Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.15 (pectinase)
 2,440 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Rhamnogalacturonan II (RG-II) is a structurally complex pectic polysaccharide present in the walls of growing plant cells. We now report that RG-II, released by endopolygalacturonase treatment of the walls of suspension-cultured sycamore cells and etiolated pea stems, exists mainly as a dimer that is cross-linked by a borate ester. The borate ester is completely hydrolyzed at room temperature within 30 min at pH 1, partially hydrolyzed between pH 2 and 4, and stable above pH 4. The dimer is formed in vitro between pH 2.4 and 6. 2 by treating monomeric RG-II (0.5 mM) with boric acid (1.2 mM); the dimer formed after 24 h at pH 3.4 and 5.0 accounts for approximately 30 and approximately 5%, respectively, of the RG-II. In contrast, the dimer accounts for approximately 80 and approximately 54% of the RG-II when the monomer is treated for 24 h at pH 3.4 and 5.0, respectively, with boric acid and 0.5 m Sr2+, Pb2+, or Ba2+. The amount of dimer formed at pH 3.4 or 5.0 is not increased by addition of 0.5 mM Ca2+, Cd2+, Cu2+, Mg2+, Ni2+, and Zn2+. Steric considerations appear to regulate dimer formation since those divalent cations that enhance dimer formation have an ionic radius >1.1 A. Our data suggest that the borate ester is located on C-2 and C-3 of two of the four 3'-linked apiosyl residues of dimeric RG-II. Our results, taken together with the results of two previous studies (Kobayashi, M., Matoh, T., and Azuma, J.-I. (1996) Plant Physiol. 110, 1017-1020; Ishii, T., and Matsunaga, T. (1996) Carbohydr. Res. 284, 1-9) provide substantial evidence that this plant cell wall pectic polysaccharide is covalently cross-linked.
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PMID:Rhamnogalacturonan-II, a pectic polysaccharide in the walls of growing plant cell, forms a dimer that is covalently cross-linked by a borate ester. In vitro conditions for the formation and hydrolysis of the dimer. 879 73

Soluble soybean polysaccharides (SSPS) extracted from soybean cotyledons are acidic polysaccharides, and exhibited a pectin-like structure. After digesting galacturonan with polygalacturonase, two novel galacturonan (GN) fragments, which were directly linked to xylosyl oligosaccharides, were obtained. One consisted of (beta-D-Xyl)7 branched at the C-3 site of 1,4-linked (alpha-D-GalA)4, and the other consisted of (beta-D-Xyl)4 branched at the C-3 site of 1,4-linked (alpha-D-GalA)3.
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PMID:Analysis of the molecular construction of xylogalacturonan isolated from soluble soybean polysaccharides. 1209 36

Soybean soluble polysaccharides (SSPS) extracted from soybean cotyledons are acidic polysaccharides and have a pectin-like structure. The results of a structural analysis of SSPS by using polygalacturonase (PGase) and rhamnogalacturonase (RGase) clarified that the main backbone consisted of galacturonan (GN) and rhamnogalacturonan (RG), which were composed of the diglycosyl repeating unit, -4)-alpha-D-GalpA-(1-->2)-alpha-L-Rhap-(1-. The side chains of beta-1,4-galactans, branched with fucose and arabinose residues, were linked to the C-4 side of rhamnose residues in the RG regions. The degree of polymerization (dps) of GN, which linked the RG regions together, was estimated to be about 4-10 residues, and some were modified with xylose residues on the C-3 side of the galacturonates. The dps of GN at the reducing end of SSPS was estimated to be about 7-9 residues. Moreover, the fragment of the basic structure of the RG region, -[4)-alpha-D-GalpA-(1-->2)-alpha-L-Rhap-(1-]2-, some of which had long-chain beta-1,4-galactans branched on the C-4 side of rhamnose residues, were liberated from SSPS by the RGase treatment. The dps of the galactan side chain was estimated to be about 43-47 residues by an analysis of the digestion products from the beta-galactosidase treatment.
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PMID:Structural studies by stepwise enzymatic degradation of the main backbone of soybean soluble polysaccharides consisting of galacturonan and rhamnogalacturonan. 1216 53