Stability constants of borate complexes of oligosaccharides

Verchère, Jean‐François; Hlaı̈bi, Miloudi

doi:10.1016/s0277-5387(00)80903-1

Cited by 60 publications

(34 citation statements)

References 12 publications

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“…This, together with the high pH of the phloem exudate (measured at close to pH 8.5), favors the formation of a bis-Suc borate complex. The complex is weak with stability constants of borateSuc complexes having log b1 and log b2 values for [LB] 21 and [L 2 B] 21 of 0.86 and 0.70, respectively (Verchere and Hlaibi, 1987). This is in contrast to the high-stability constants for Fru-borate complexes of 2.82 (log b1) and 4.97 (log b2) for the [LB] 21 and [L 2 B] 21 complexes, respectively (Verchere and Hlaibi, 1987).…”

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confidence: 99%

The Mechanism of Boron Mobility in Wheat and Canola Phloem

et al. 2010

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Low-molecular-weight borate complexes were isolated from canola (Brassica napus) and wheat (Triticum aestivum) phloem exudates, as well as the cytoplasm of the fresh-water alga Chara corallina, and identified using matrix-assisted laser desorption/ ionization time-of-flight mass spectrometry. Phloem exudate was collected from field-grown canola inflorescence stalks by shallow incision, while wheat phloem exudate was collected by aphid stylectomy. Chara cytoplasm was collected by careful manual separation of the cell wall, vacuole, and cytosolic compartments. Matrix-assisted laser desorption/ionization time-offlight mass spectrometry showed the presence of isotopic borate complexes, at mass-to-charge ratio of 690.22/691.22 in the canola and wheat phloem and at 300.11/301.11 in canola phloem and Chara cytoplasm. Using reference compounds, the borate complexes with mass-to-charge ratio 690.22/691.22 was identified as a bis-sucrose (Suc) borate complex in which the 4,6-hydroxyl pairs from the two a-glucopyranoside moieties formed an [L 2 B] 21 complex. Further investigation using liquid chromatography electrospray ionization triple quadrupole mass spectrometry analysis confirmed the presence of the bis-Suc borate complex in wheat phloem with a concentration up to 220 mM. The 300.11/301.11 complex was putatively identified as a bis-N-acetyl-serine borate complex but its concentration was below the detection limits of the liquid chromatography electrospray ionization triple quadrupole mass spectrometer so could not be quantified. The presence of borate complexes in the phloem provides a mechanistic explanation for the observed phloem boron mobility in canola and wheat and other species that transport Suc as their primary photoassimilate.Boron (B) is an essential element for plant growth (Warington, 1923) and it plays a structural role in the cell wall where it cross-links the pectic fractions of the dimeric polysaccharide complex known as RG-II (Matoh et al

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confidence: 99%

The Mechanism of Boron Mobility in Wheat and Canola Phloem

et al. 2010

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“…A study was undertaken to investigate the complexation of borate with carbohydrates using pH measurements method. Similar procedure of the calculation of stability constants as reported in the literature 3 was followed in this study. The values of thermodynamic parameters of borate-carbohydrate complexes have also been presented.…”

Section: Introductionmentioning

confidence: 79%

“…The parameters β 1 and β 2 were obtained from polynomial fitting of the experimental data using iteration method 3 . The values of β 1 for carbohydrates-borate complexes are presented in Table 1.…”

Section: Resultsmentioning

confidence: 99%

“…The study of the formation of complexes between borate and polyhydroxy compounds has been received considerable attention since few decades [1][2][3] . Such studies provide an important tool in conformational analysis of carbohydrates and are used in a variety of separation and chromatographic techniques.…”

Section: Introductionmentioning

confidence: 99%

“…These reactions are used for the titrimetric determination of boron 5 . The formation of borate complexes of several mono-, di-and trisaccharides in aqueous solution at constant temperature and ionic strength using potentiometric method was reported in the literature 3 . A study was undertaken to investigate the complexation of borate with carbohydrates using pH measurements method.…”

Section: Introductionmentioning

confidence: 99%

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