Effect of the Addition of Electrolytes on the Partition Coefficients, Activity Coefficients, and Acid Dissociation Constants of Carnitine and its Acetyl and Propionyl Derivatives

Maria, Paolo De; Fontana, Antonella; Frascri, Sara; Gargaro, Giuseppe; Spinelli, Domenico; Tinti, Maria Ornella

doi:10.1002/jps.2600830530

Cited by 10 publications

(2 citation statements)

References 13 publications

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“…This ionization of the carboxylate is described by the acid dissociation constant, pK a . The pK a of carnitine in water at 25°C has been reported to be 3.72 whereas that of both acetylcarnitine and propionylcarnitine was found to be 3.58 (De Maria et al 1994), suggesting that increasing the acyl chainlength does not alter the pK a if the acylcarnitine is present as a monomer in water. However, the pK a of the carboxyl group of long chain acylcarnitines will be different because they aggregate in aqueous solution and hence their pK a values will be affected by both the polarity of the interface as well as the surface electrostatics (cf.…”

Section: Phase Transitions Of Stearoylcarnitine-turbidimetric and Dscmentioning

confidence: 89%

Studies on the Critical Micellar Concentration and Phase Transitions of Stearoylcarnitine

Kamlekar

Swamy

2006

Bioscience Reports

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The critical micellar concentration (CMC) of stearoylcarnitine was determined at different pH values at room temperature by fluorescence spectroscopy, monitoring the spectral changes of 8-anilinonaphthalene-1-sulfonate (ANS). The CMC was found to vary with pH, increasing from about 10 microM at pH 3.0 to ca. 25 microM at pH 7.0, but decreasing slightly with further increase in pH to approximately 19 microM at pH 10.0. Differential scanning calorimetry (DSC) shows that stearoylcarnitine dispersed in water at low concentration undergoes a broad thermotropic phase transition at 44.5 degrees C, with a transition enthalpy of 15.0 kcal/mol. The transition temperature (Tt) shifts to ca. 50.5 degrees C in the presence of 1 mM EDTA or when the concentration is increased significantly. The turbidity of aqueous dispersions of stearoylcarnitine was found to be considerably high at low temperatures, which decreases quite abruptly over a short temperature range, indicating that a transition occurs from a phase of large aggregates to one of much smaller aggregates, most likely micelles. The phase transition temperature was determined as 29.1 degrees C at pH 3.0, which increased with increasing pH up to a value of 55.3 degrees C at pH 8.6 and remains nearly constant thereafter up to pH 11.2. The pH dependence of CMC and Tt suggest that the pKa of the carboxyl group of long chain acylcarnitines shifts to higher temperatures upon aggregation (micelles or bilayer membranes).

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Section: Phase Transitions Of Stearoylcarnitine-turbidimetric and Dscmentioning

confidence: 89%

Studies on the Critical Micellar Concentration and Phase Transitions of Stearoylcarnitine

Kamlekar

Swamy

2006

Bioscience Reports

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“…The carboxylic acid group of the (±)-carnitine guest, (CH 3 ) 3 NCH 2 CH-(OH)CH 2 CO 2 H + , has a pK a of 3.78. 37 The titrations of carnitine [7] ) for cucurbit [7]uril with cholines, phosphonium analogues, and related guests in D 2 O at 25 + as the competitor. p H3 protons.…”

Section: Host-guest Stability Constantsmentioning

confidence: 99%

Cucurbit[7]urilhost–guest complexes of cholines and phosphonium cholines in aqueous solution

Wyman

Macartney

2010

Org. Biomol. Chem.

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The neutral host cucurbit[7]uril forms very stable complexes with a series of cationic cholines (R(3)NCH(2)CH(2)OR'(+)) and their phosphonium analogues (R(3)PCH(2)CH(2)OR'(+)) (R(3) = Me(3), Et(3), or Me(2)Bz, or R(3)N = quinuclidinium, and R' = H, COCH(3), CO(CH(2))(2)CH(3), or PO(3)H), and (+/-)-carnitine, in aqueous solution. The complexation behaviour has been investigated using (1)H and (31)P NMR spectroscopies, and ESI mass spectrometry. The complexation-induced chemical shift changes of the guests clearly indicate the effects of replacing the N(CH(3))(3)(+) end group by P(CH(3))(3)(+), and changing the nature of R on the position of the guest with respect to the CB[7] cavity and its polar portal-lining carbonyl groups. This study demonstrates that molecular recognition of cholines in aqueous solution is achievable with a neutral host without the need for aromatic walls for cation-pi interactions.

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Kinetics of breakdown of vesicles from didodecyldimethylammonium bromide induced by single chain surfactants and by osmotic stress in aqueous solution

Fontana

Maria

Siani

et al. 2003

Colloids and Surfaces B: Biointerfaces

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Effect of the Addition of Electrolytes on the Partition Coefficients, Activity Coefficients, and Acid Dissociation Constants of Carnitine and its Acetyl and Propionyl Derivatives

Cited by 10 publications

References 13 publications

Studies on the Critical Micellar Concentration and Phase Transitions of Stearoylcarnitine

Studies on the Critical Micellar Concentration and Phase Transitions of Stearoylcarnitine

Cucurbit[7]urilhost–guest complexes of cholines and phosphonium cholines in aqueous solution

Kinetics of breakdown of vesicles from didodecyldimethylammonium bromide induced by single chain surfactants and by osmotic stress in aqueous solution

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