{"count":839,"next":"http://glycodata.org/api/gdd/glyco-properties/?format=json&page=15","previous":"http://glycodata.org/api/gdd/glyco-properties/?format=json&page=13","results":[{"id":261,"dataset":"carbohydrate","entity":"methyl 2,4-di-O-methyl-alpha-D-galactopyranosiduronic acid (methyl ester)","entity_group":"","entity_class":"glycoside","property":"pKa","property_key":"pka","value":"3.22","unit":"pKa","value_reported":"3.22","unit_reported":"pKa","method":"Experiment","method_detail":"carboxyl pK, compound IV, 20 C, discontinuous potentiometric titration","conditions":"carboxyl pK, compound IV, 20 C, discontinuous potentiometric titration","conditions_detail":"carboxyl pK, compound IV, 20 C, discontinuous potentiometric titration | group: carboxyl | temperature C: 20","doi":"","source_url":"https://www.chemicalpapers.com/file_access.php?file=324a478.pdf","year":"1978","confidence":"high","comments":"\"Table 1 ... Methyl 2,4-di-O-methyl-a-D-galactopyranosiduronic ... 3.22±0.01 ... ApK -0.29\"  — Chem. Zvesti 32(4) 478-485 (1978), Table 1 compound IV.  [Kohn, R.; Kovac, P., 1978, confidence: high]"},{"id":262,"dataset":"carbohydrate","entity":"methyl 2,3-di-O-methyl-alpha-D-galactopyranosiduronic acid (methyl ester)","entity_group":"","entity_class":"glycoside","property":"pKa","property_key":"pka","value":"3.42","unit":"pKa","value_reported":"3.42","unit_reported":"pKa","method":"Experiment","method_detail":"carboxyl pK, compound V, 20 C, discontinuous potentiometric titration","conditions":"carboxyl pK, compound V, 20 C, discontinuous potentiometric titration","conditions_detail":"carboxyl pK, compound V, 20 C, discontinuous potentiometric titration | group: carboxyl | temperature C: 20","doi":"","source_url":"https://www.chemicalpapers.com/file_access.php?file=324a478.pdf","year":"1978","confidence":"high","comments":"\"Table 1 ... Methyl 2,3-di-O-methyl-a-D-galactopyranosiduronic ... 3.42±0.01 ... ApK -0.09\"  — Chem. Zvesti 32(4) 478-485 (1978), Table 1 compound V.  [Kohn, R.; Kovac, P., 1978, confidence: high]"},{"id":263,"dataset":"carbohydrate","entity":"methyl 2,3,4-tri-O-methyl-alpha-D-galactopyranosiduronic acid (methyl ester)","entity_group":"","entity_class":"glycoside","property":"pKa","property_key":"pka","value":"3.13","unit":"pKa","value_reported":"3.13","unit_reported":"pKa","method":"Experiment","method_detail":"carboxyl pK, compound VI (fully methylated D-galacturonic derivative), 20 C, discontinuous potentiometric titration","conditions":"carboxyl pK, compound VI (fully methylated D-galacturonic derivative), 20 C, discontinuous potentiometric titration","conditions_detail":"carboxyl pK, compound VI (fully methylated D-galacturonic derivative), 20 C, discontinuous potentiometric titration | group: carboxyl | temperature C: 20","doi":"","source_url":"https://www.chemicalpapers.com/file_access.php?file=324a478.pdf","year":"1978","confidence":"high","comments":"\"Table 1 ... Methyl 2,3,4-tri-O-methyl-a-D-galactopyranosiduronic ... 3.13±0.01 ... ApK -0.38\"  — Chem. Zvesti 32(4) 478-485 (1978), Table 1 compound VI; lowest pK of the galacto series.  [Kohn, R.; Kovac, P., 1978, confidence: high]"},{"id":264,"dataset":"carbohydrate","entity":"methyl 2,3,4-tri-O-methyl-alpha-D-glucopyranosiduronic acid (methyl ester)","entity_group":"","entity_class":"glycoside","property":"pKa","property_key":"pka","value":"3.03","unit":"pKa","value_reported":"3.03","unit_reported":"pKa","method":"Experiment","method_detail":"carboxyl pK, compound VIII (fully methylated D-glucuronic derivative), 20 C, discontinuous potentiometric titration","conditions":"carboxyl pK, compound VIII (fully methylated D-glucuronic derivative), 20 C, discontinuous potentiometric titration","conditions_detail":"carboxyl pK, compound VIII (fully methylated D-glucuronic derivative), 20 C, discontinuous potentiometric titration | group: carboxyl | temperature C: 20","doi":"","source_url":"https://www.chemicalpapers.com/file_access.php?file=324a478.pdf","year":"1978","confidence":"high","comments":"\"Table 1 ... Methyl 2,3,4-tri-O-methyl-a-D-glucopyranosiduronic ... 3.03 ±0.02 ... ApK -0.25\"  — Chem. Zvesti 32(4) 478-485 (1978), Table 1 compound VIII.  [Kohn, R.; Kovac, P., 1978, confidence: high]"},{"id":265,"dataset":"carbohydrate","entity":"4-deoxy-beta-L-threo-hex-4-enopyranuronic acid (methyl ester glycoside)","entity_group":"","entity_class":"uronic acid","property":"pKa","property_key":"pka","value":"3.1","unit":"pKa","value_reported":"3.1","unit_reported":"pKa","method":"Experiment","method_detail":"carboxyl pK, compound IX, 4,5-unsaturated uronic acid (pectate/pectin lyase product), 20 C, discontinuous potentiometric titration","conditions":"carboxyl pK, compound IX, 4,5-unsaturated uronic acid (pectate/pectin lyase product), 20 C, discontinuous potentiometric titration","conditions_detail":"carboxyl pK, compound IX, 4,5-unsaturated uronic acid (pectate/pectin lyase product), 20 C, discontinuous potentiometric titration | group: carboxyl | temperature C: 20","doi":"","source_url":"https://www.chemicalpapers.com/file_access.php?file=324a478.pdf","year":"1978","confidence":"high","comments":"\"Table 1 ... Methyl 4-deoxy-j3-L-fhreo-hex-4-enopyranosiduronic ... 3.10±0.01 ... ApK -0.41\"  — Chem. Zvesti 32(4) 478-485 (1978), Table 1 compound IX; unsaturated uronic acid formed by beta-elimination in pectin degradation.  [Kohn, R.; Kovac, P., 1978, confidence: high]"},{"id":266,"dataset":"carbohydrate","entity":"D-glucuronic acid","entity_group":"","entity_class":"uronic acid","property":"pKa","property_key":"pka","value":"3.24","unit":"pKa","value_reported":"3.24","unit_reported":"pKa","method":"Experiment","method_detail":"carboxyl pK, 25 C, literature value cited by Kohn & Kovac (ref [14], Zverev 1960)","conditions":"carboxyl pK, 25 C, literature value cited by Kohn & Kovac (ref [14], Zverev 1960)","conditions_detail":"carboxyl pK, 25 C, literature value cited by Kohn & Kovac (ref [14], Zverev 1960) | group: carboxyl | temperature C: 25","doi":"","source_url":"https://www.chemicalpapers.com/file_access.php?file=324a478.pdf","year":"1978","confidence":"medium","comments":"\"The following pK values for D-glucuronic acid can be found in the literature: 3.33 [19], 3.20 [21], 3.24 (25°C) [14], 3.23 (25°C) [23]\"  — Literature compilation value cited within Kohn & Kovac (1978); original ref [14] Zverev 1960.  [Kohn, R.; Kovac, P., 1978, confidence: medium]"},{"id":267,"dataset":"carbohydrate","entity":"D-galacturonic acid","entity_group":"","entity_class":"uronic acid","property":"pKa","property_key":"pka","value":"3.47","unit":"pKa","value_reported":"3.47","unit_reported":"pKa","method":"Experiment","method_detail":"carboxyl pK, 25 C, literature value cited by Kohn & Kovac (ref [23], Holvik & Hoiland 1977)","conditions":"carboxyl pK, 25 C, literature value cited by Kohn & Kovac (ref [23], Holvik & Hoiland 1977)","conditions_detail":"carboxyl pK, 25 C, literature value cited by Kohn & Kovac (ref [23], Holvik & Hoiland 1977) | group: carboxyl | temperature C: 25","doi":"","source_url":"https://www.chemicalpapers.com/file_access.php?file=324a478.pdf","year":"1978","confidence":"medium","comments":"\"For D-galacturonic acid the following pK have been determined: 3.42 (27°C) [20], 3.42 [21], 3.49 (23.6°C) [22], 3.47 (25°C) [23]\"  — Literature compilation value cited within Kohn & Kovac (1978); original ref [23] Holvik & Hoiland, J. Chem. Thermodyn. 9, 345 (1977).  [Kohn, R.; Kovac, P., 1978, confidence: medium]"},{"id":268,"dataset":"carbohydrate","entity":"D-galacturonic acid","entity_group":"","entity_class":"uronic acid","property":"pKa","property_key":"pka","value":"3.51","unit":"pKa","value_reported":"3.51","unit_reported":"pKa","method":"Review","method_detail":"carboxyl pKa of galacturonic acid, value cited in microbiology study of pectin fermentation","conditions":"carboxyl pKa of galacturonic acid, value cited in microbiology study of pectin fermentation","conditions_detail":"carboxyl pKa of galacturonic acid, value cited in microbiology study of pectin fermentation | group: carboxyl","doi":"10.1128/AEM.07617-11","source_url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC3416429/","year":"2012","confidence":"high","comments":"\"Galacturonic acid is the uronic acid of galactose and has a dissociation constant (pKa) of 3.51\"  — Independent secondary citation of the carboxyl pKa, consistent with Kohn & Kovac (1978).  [Huisjes, E.H.; et al., 2012, confidence: high]"},{"id":269,"dataset":"carbohydrate","entity":"alpha-L-idopyranosyluronic acid 2-sulphate (heparin iduronic acid)","entity_group":"","entity_class":"uronic acid","property":"pKa","property_key":"pka","value":"3.13","unit":"pKa","value_reported":"3.13","unit_reported":"pKa","method":"Experiment","method_detail":"carboxylate pKa determined using heparin, 13C-NMR spectroscopy at various pH","conditions":"carboxylate pKa determined using heparin, 13C-NMR spectroscopy at various pH","conditions_detail":"carboxylate pKa determined using heparin, 13C-NMR spectroscopy at various pH | group: carboxyl","doi":"10.1042/bj2780689","source_url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC1151401/","year":"1991","confidence":"high","comments":"\"The pKa values of their carboxylate groups were determined as 3.13 (using heparin), 2.79 (using heparin) and 3.0 (predicted by using model compounds) respectively\"  — Biochem J 278(Pt 3):689-695. alpha-L-IdoA 2-sulphate residue in heparin.  [Wang, H.M.; Loganathan, D.; Linhardt, R.J., 1991, confidence: high]"},{"id":270,"dataset":"carbohydrate","entity":"beta-D-glucopyranosyluronic acid (heparin glucuronic acid)","entity_group":"","entity_class":"uronic acid","property":"pKa","property_key":"pka","value":"2.79","unit":"pKa","value_reported":"2.79","unit_reported":"pKa","method":"Experiment","method_detail":"carboxylate pKa determined using heparin, 13C-NMR spectroscopy at various pH","conditions":"carboxylate pKa determined using heparin, 13C-NMR spectroscopy at various pH","conditions_detail":"carboxylate pKa determined using heparin, 13C-NMR spectroscopy at various pH | group: carboxyl","doi":"10.1042/bj2780689","source_url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC1151401/","year":"1991","confidence":"high","comments":"\"The pKa values of their carboxylate groups were determined as 3.13 (using heparin), 2.79 (using heparin) and 3.0 (predicted by using model compounds) respectively\"  — Biochem J 278(Pt 3):689-695. beta-D-GlcA residue in heparin.  [Wang, H.M.; Loganathan, D.; Linhardt, R.J., 1991, confidence: high]"},{"id":271,"dataset":"carbohydrate","entity":"alpha-L-idopyranosyluronic acid (heparin, predicted)","entity_group":"","entity_class":"uronic acid","property":"pKa","property_key":"pka","value":"3","unit":"pKa","value_reported":"3.0","unit_reported":"pKa","method":"Experiment","method_detail":"carboxylate pKa predicted using model compounds (13C-NMR study of heparin)","conditions":"carboxylate pKa predicted using model compounds (13C-NMR study of heparin)","conditions_detail":"carboxylate pKa predicted using model compounds (13C-NMR study of heparin) | group: carboxyl","doi":"10.1042/bj2780689","source_url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC1151401/","year":"1991","confidence":"medium","comments":"\"and 3.0 (predicted by using model compounds) respectively\"  — Biochem J 278(Pt 3):689-695. Value is predicted (not directly measured) for non-sulphated alpha-L-IdoA in heparin.  [Wang, H.M.; Loganathan, D.; Linhardt, R.J., 1991, confidence: medium]"},{"id":272,"dataset":"carbohydrate","entity":"N-acetylneuraminic acid (Neu5Ac, sialic acid)","entity_group":"","entity_class":"sialic acid","property":"pKa","property_key":"pka","value":"2.6","unit":"pKa","value_reported":"2.6","unit_reported":"pKa","method":"Review","method_detail":"C-1 carboxylate pKa of Neu5Ac; the electron-withdrawing carboxylate is attached to the C-2 anomeric carbon","conditions":"C-1 carboxylate pKa of Neu5Ac; the electron-withdrawing carboxylate is attached to the C-2 anomeric carbon","conditions_detail":"C-1 carboxylate pKa of Neu5Ac; the electron-withdrawing carboxylate is attached to the C-2 anomeric carbon | group: carboxyl","doi":"10.1101/glycobiology.4e.15","source_url":"https://www.ncbi.nlm.nih.gov/books/NBK579976/","year":"2022","confidence":"high","comments":"\"The most common Sia form in humans is Neu5Ac, a relatively strong acid (pKa=2.6) with the electron-withdrawing C-1 carboxylate attached to the C-2 anomeric carbon.\"  — Reference textbook (Cold Spring Harbor). Lower pKa than typical carboxylic acids due to adjacent ring oxygen / anomeric carbon.  [Lewis, A.L.; Chen, X.; Schnaar, R.L.; Varki, A., 2022, confidence: high]"},{"id":273,"dataset":"carbohydrate","entity":"L-ascorbic acid (vitamin C)","entity_group":"","entity_class":"sugar acid","property":"pKa","property_key":"pka","value":"4.17","unit":"pKa","value_reported":"4.17","unit_reported":"pKa","method":"Experiment","method_detail":"pK1 (first dissociation, C-3 enediol OH), from Merck Index compilation","conditions":"pK1 (first dissociation, C-3 enediol OH), from Merck Index compilation","conditions_detail":"pK1 (first dissociation, C-3 enediol OH), from Merck Index compilation | group: enediol_OH","doi":"","source_url":"https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/54670067/JSON?heading=Dissociation+Constants","year":"2006","confidence":"high","comments":"\"pK1 = 4.17; pK2 = 11.57\"  — Ascorbic acid is a sugar acid (lactone of a hexonic acid); first proton is the C-3 enediol OH.  [O'Neil, M.J. (ed.), The Merck Index, 14th ed. (2006), p. 136, 2006, confidence: high]"},{"id":274,"dataset":"carbohydrate","entity":"L-ascorbic acid (vitamin C)","entity_group":"","entity_class":"sugar acid","property":"pKa","property_key":"pka","value":"11.57","unit":"pKa","value_reported":"11.57","unit_reported":"pKa","method":"Experiment","method_detail":"pK2 (second dissociation, C-2 enediol OH), from Merck Index compilation","conditions":"pK2 (second dissociation, C-2 enediol OH), from Merck Index compilation","conditions_detail":"pK2 (second dissociation, C-2 enediol OH), from Merck Index compilation | group: enediol_OH","doi":"","source_url":"https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/54670067/JSON?heading=Dissociation+Constants","year":"2006","confidence":"high","comments":"\"pK1 = 4.17; pK2 = 11.57\"  — Second (much weaker) ionization of ascorbic acid.  [O'Neil, M.J. (ed.), The Merck Index, 14th ed. (2006), p. 136, 2006, confidence: high]"},{"id":275,"dataset":"carbohydrate","entity":"L-ascorbic acid (vitamin C)","entity_group":"","entity_class":"sugar acid","property":"pKa","property_key":"pka","value":"4.7","unit":"pKa","value_reported":"4.7","unit_reported":"pKa","method":"Experiment","method_detail":"pKa at 10 C, IUPAC compilation (Kortum et al. 1961)","conditions":"pKa at 10 C, IUPAC compilation (Kortum et al. 1961)","conditions_detail":"pKa at 10 C, IUPAC compilation (Kortum et al. 1961) | group: enediol_OH | temperature C: 10","doi":"","source_url":"https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/54670067/JSON?heading=Dissociation+Constants","year":"1961","confidence":"high","comments":"\"pKa = 4.70 at 10 °C\"  — Temperature 10 C (hence higher than the 25 C value of 4.17); first dissociation.  [Kortum, G.; Vogel, W.; Andrussow, K. (IUPAC, Dissociation Constants of Organic Acids in Aqueous Solution, Butterworth, 1961), 1961, confidence: high]"},{"id":276,"dataset":"carbohydrate","entity":"D-gluconic acid","entity_group":"","entity_class":"sugar acid","property":"pKa","property_key":"pka","value":"3.62","unit":"pKa","value_reported":"3.62","unit_reported":"pKa","method":"Experiment","method_detail":"carboxyl pKa (acidic), ChEMBL value reported in PubChem Dissociation Constants section","conditions":"carboxyl pKa (acidic), ChEMBL value reported in PubChem Dissociation Constants section","conditions_detail":"carboxyl pKa (acidic), ChEMBL value reported in PubChem Dissociation Constants section | group: carboxyl","doi":"","source_url":"https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/10690/JSON?heading=Dissociation+Constants","year":"2025","confidence":"high","comments":"\"Acidic pKa: 3.62 ... Tested as SID 103629256 in AID 781325\"  — D-gluconic acid is an aldonic acid (oxidation product of glucose at C-1).  [ChEMBL (via PubChem), 2025, confidence: high]"},{"id":277,"dataset":"carbohydrate","entity":"D-gluconic acid","entity_group":"","entity_class":"sugar acid","property":"pKa","property_key":"pka","value":"3.6","unit":"pKa","value_reported":"3.6","unit_reported":"pKa","method":"Experiment","method_detail":"carboxyl pKa derived from Ka = 2.5e-4 at 25 C (Merck Index); pKa = -log10(2.5e-4) = 3.60","conditions":"carboxyl pKa derived from Ka = 2.5e-4 at 25 C (Merck Index); pKa = -log10(2.5e-4) = 3.60","conditions_detail":"carboxyl pKa derived from Ka = 2.5e-4 at 25 C (Merck Index); pKa = -log10(2.5e-4) = 3.60 | group: carboxyl | temperature C: 25","doi":"","source_url":"https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/10690/JSON?heading=Dissociation+Constants","year":"1989","confidence":"high","comments":"\"Ka value: 2.5×10⁻⁴ @ 25°C\"  — pKa computed from the reported Ka (2.5e-4) at 25 C; consistent with the ChEMBL value 3.62.  [Budavari, S. (ed.), The Merck Index, 11th ed., 1989, confidence: high]"},{"id":278,"dataset":"carbohydrate","entity":"D-glucaric acid (saccharic acid)","entity_group":"","entity_class":"sugar acid","property":"pKa","property_key":"pka","value":"3.01","unit":"pKa","value_reported":"3.01","unit_reported":"pKa","method":"Review","method_detail":"pKa1, first carboxyl dissociation of the aldaric (dicarboxylic) acid","conditions":"pKa1, first carboxyl dissociation of the aldaric (dicarboxylic) acid","conditions_detail":"pKa1, first carboxyl dissociation of the aldaric (dicarboxylic) acid | group: carboxyl","doi":"","source_url":"https://grokipedia.com/page/Saccharic_acid","year":"2025","confidence":"low","comments":"\"Saccharic acid (also known as D-glucaric acid) has pKa values of 3.01 and 3.94\"  — Aldaric acid with two carboxyl groups. Secondary compilation source; pKa1 of the diprotic acid. Confidence low pending a primary potentiometric reference.  [Grokipedia (Saccharic acid), 2025, confidence: low]"},{"id":279,"dataset":"carbohydrate","entity":"D-glucaric acid (saccharic acid)","entity_group":"","entity_class":"sugar acid","property":"pKa","property_key":"pka","value":"3.94","unit":"pKa","value_reported":"3.94","unit_reported":"pKa","method":"Review","method_detail":"pKa2, second carboxyl dissociation of the aldaric (dicarboxylic) acid","conditions":"pKa2, second carboxyl dissociation of the aldaric (dicarboxylic) acid","conditions_detail":"pKa2, second carboxyl dissociation of the aldaric (dicarboxylic) acid | group: carboxyl","doi":"","source_url":"https://grokipedia.com/page/Saccharic_acid","year":"2025","confidence":"low","comments":"\"Saccharic acid (also known as D-glucaric acid) has pKa values of 3.01 and 3.94\"  — Second carboxyl dissociation. Secondary compilation source; confidence low pending a primary reference.  [Grokipedia (Saccharic acid), 2025, confidence: low]"},{"id":280,"dataset":"carbohydrate","entity":"D-glucosamine","entity_group":"","entity_class":"amino sugar","property":"pKa","property_key":"pka","value":"7.58","unit":"pKa","value_reported":"7.58","unit_reported":"pKa","method":"Experiment","method_detail":"protonated amino group (NH3+) pKa; value from Bichsel & Von Gunten (2000)","conditions":"protonated amino group (NH3+) pKa; value from Bichsel & Von Gunten (2000)","conditions_detail":"protonated amino group (NH3+) pKa; value from Bichsel & Von Gunten (2000) | group: amino","doi":"10.1021/es9914590","source_url":"https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/439213/JSON?heading=Dissociation+Constants","year":"2000","confidence":"high","comments":"\"pKa = 7.58 ... Bichsel Y, Von Gunten U; Environ Sci Technol 34: 2784-91 (2000)\"  — Amino sugar; ionizable group is the C-2 ammonium.  [Bichsel, Y.; Von Gunten, U., Environ. Sci. Technol. 34, 2784-2791, 2000, confidence: high]"}]}