{"id":"3319781b-4ab3-55de-8c24-93ac11621aef","stable_key":"d17caac5-7018-5ca8-9e96-95afeb384bc4:pectin-borate-crosslink","predicate":"crosslinks","statement":"A borate ester bridges two RG-II molecules in the isolated plant-wall dimer.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"3f68d8ac-97e3-5e32-b099-9988430ca99e","mechanism_event_label":"Boron is part of a plant pectin cross-link.","subject":{"id":"04e68eab-58b9-5be0-95b1-0739fc0699ff","slug":"borate","display_name":"Tetrahydroxyborate / B(OH)4−","entity_type_key":"ion"},"object":{"id":"93773f2f-bc93-522a-ac6f-23ea52bc14dd","slug":"borate-rgii-dimer","display_name":"Borate-diester-linked RG-II dimer","entity_type_key":"chemical_species"},"evidence_count":1,"mechanism_event":{"id":"3f68d8ac-97e3-5e32-b099-9988430ca99e","stable_key":"d17caac5-7018-5ca8-9e96-95afeb384bc4:pectin-borate-crosslink-event","event_type":"biochemical_relationship","label":"Boron is part of a plant pectin cross-link.","description":"A borate ester bridges two RG-II molecules in the isolated plant-wall dimer.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"ef09fcc7-de79-5e63-b329-8a148639469e","slug":"pectic-rhamnogalacturonan-ii","display_name":"Pectic rhamnogalacturonan II / RG-II","entity_type_key":"chemical_species"},"role":"crosslinked_polysaccharide","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"04e68eab-58b9-5be0-95b1-0739fc0699ff","slug":"borate","display_name":"Tetrahydroxyborate / B(OH)4−","entity_type_key":"ion"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"93773f2f-bc93-522a-ac6f-23ea52bc14dd","slug":"borate-rgii-dimer","display_name":"Borate-diester-linked RG-II dimer","entity_type_key":"chemical_species"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""}]},"contexts":[{"dimension":"evidence_span","value_text":"{\"source_cache\": \"artifacts/pectin-research/8798473.abstract.txt\", \"locator\": \"Primary indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"4435a2ce2789d98a56c321a69ee20acbcafbff021acf2543a0b9126ebaa375fe\", \"start_char\": 0, \"end_char\": 1643, \"text_sha256\": \"4435a2ce2789d98a56c321a69ee20acbcafbff021acf2543a0b9126ebaa375fe\"}","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Plant cell-wall isolation and in-vitro dimer chemistry","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"Isolated RG-II, boric acid and controlled pH","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Plant structural chemistry is not a human pectin or boron supplementation mechanism.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Pectin research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"pectin","display_name":"Pectin, structurally heterogeneous plant polysaccharides","entity_type_key":"chemical_species"}},{"dimension":"organism","value_text":"Sycamore cell cultures and pea stems; purified plant polysaccharide","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"Boron is part of a plant pectin cross-link.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[pectin-p8798473] 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. (1996). https://pubmed.ncbi.nlm.nih.gov/8798473/ DOI: 10.1074/jbc.271.37.22923","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Plant cell wall","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"e69a15df-f750-5319-9bb1-d102f9e415f0","evidence_kind":"source_excerpt","locator":"Lines 334-345","start_line":334,"end_line":345,"excerpt":"### pectin-borate-crosslink\nA borate ester bridges two RG-II molecules in the isolated plant-wall dimer.\nCondition category: normal\nnutrient_topic: Pectin research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: Boron is part of a plant pectin cross-link.\norganism: Sycamore cell cultures and pea stems; purified plant polysaccharide\ntissue_or_cell_type: Plant cell wall\nexperimental_model: Plant cell-wall isolation and in-vitro dimer chemistry\nlimitations: Plant structural chemistry is not a human pectin or boron supplementation mechanism.\nexposure: Isolated RG-II, boric acid and controlled pH\nevidence_span: {\"source_cache\": \"artifacts/pectin-research/8798473.abstract.txt\", \"locator\": \"Primary indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"4435a2ce2789d98a56c321a69ee20acbcafbff021acf2543a0b9126ebaa375fe\", \"start_char\": 0, \"end_char\": 1643, \"text_sha256\": \"4435a2ce2789d98a56c321a69ee20acbcafbff021acf2543a0b9126ebaa375fe\"}\n[pectin-p8798473] 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. (1996). https://pubmed.ncbi.nlm.nih.gov/8798473/ DOI: 10.1074/jbc.271.37.22923","model_system":"Plant cell-wall isolation and in-vitro dimer chemistry","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [pectin-p8798473] 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. 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