Partition of amphiphilic molecules into phospholipid vesicles and human erythrocyte ghosts: measurements by ultraviolet difference spectroscopy

Abstract

Molar partition coefficients for chlorpromazine and methochlorpromazine between phospholipid vesicles or human erythrocyte ghosts and buffer are determined by ultraviolet difference spectroscopy. The partition coefficients between small unilamellar egg phosphatidylcholine vesicles and buffer at pH 7.4 are 4.4 X 10(5) for chlorpromazine and 0.8 X 10(5) for methochlorpromazine, determined with 10 microM amphiphile. An increase in the partition of chlorpromazine into vesicles is seen as the pH is increased to the pKa of chlorpromazine at 9.2. Chlorpromazine also partitions preferentially into fluid-phase phospholipid compared to solid-phase phospholipid. Molar partition coefficients between unsealed human erythrocyte ghosts and buffer at pH 8.0 with 10 microM amphiphile are determined to be 6.5 X 10(5) for chlorpromazine and 2.5 X 10(5) for methochlorpromazine. Difference spectroscopy is an equilibrium technique that does not require separation of bound from free amphiphile, as do many other methods of determining membrane-buffer partition coefficients. This method is useful for any amphiphile that has an appreciable absorbance below its critical micelle concentration and whose absorbance is sensitive to environment.

Effects of Phosphatidylserine and Phosphatidylethanolamine Content on Partitioning of Triflupromazine and Chlorpromazine between Phosphatidylcholine-Aminophospholipid Bilayer Vesicles and Water Studied by Second-Derivative Spectrophotometry

“…Calculation of Molar Partition Coefficients The molar partition coefficient (K p ) of phenothiazine between the vesicles and water is defined as, 5,15) (1) As the background signal effect based on the vesicles can be eliminated in the second derivative spectra, the derivative intensity difference (DD) of phenothiazine before and after the addition of the vesicles measured at a specific wavelength is proportional to the concentration of phenothiazine in the vesicles, and thus we can get Eq. 2 from Eq.…”

“…The molar partition coefficient (K p ) of phenothiazine between the vesicles and water is defined as, 5,15) (1) To assess the affinity of psychotropic phenothiazine drugs, triflupromazine (TFZ) and chlorpromazine (CPZ), for the membranes of central nervous system and the other organs in the body, the partition coefficients (K p s) of these drugs to phosphatidylcholine (PC)-phosphatidylserine (PS) and PC-phosphatidylethanolamine (PE) small and large unilamellar vesicles (SUV, LUV) were examined by a second-derivative spectrophotometric method, since PS is abundantly contained in the membranes of the central nervous system and PE is distributed widely in the membranes of the organs in the body. Size and preparation methods of the vesicles did not affect the K p values at each aminophospholipid content suggesting that the partition of the phenothiazine drugs was not affected by the structural differences in the vesicles such as their curvature or asymmetric distribution of the phospholipids between the outer and inner layers of the bilayer membranes.…”

Kinetics Study of Malachite Green Fading in the Presence of TX-100, DTAB and SDS

“…The red shift has been previously reported for other compounds upon going from polar to apolar solvents, as a result of hydrophobic interaction. [22][23][24] It seems that TX-100 molecules decrease dielectric constant of the MG + micro-environment. According to Hughs-Ingold rules for nucleophilic substitution reactions, 25,26 formation of the neutral carbinol base from two oppositely charged reactants is more favorable in lower dielectric constant media and thus with increase in TX-100 concentration, the rate of MG + fading increases in the first region.…”

Anti‐idiotypic antibody identifies the structural similarity between the phosphatidylcholine‐specific monoclonal antibody and phosphatidylcholine‐specific lipid transfer protein

“…Since the reactivity profile of JE-1 showed a close similarity to that of the PC-specific lipid transfer protein [7,8], the cross-reactivity of the anti-Id with the PC-specific lipid transfer protein purified from bovine liver was examined. As shown in Fig.…”

“…In the previous study we established a series of mAbs that specifically recognizes PC [7]. One of the mAbs, designated JE-I , showed a reactivity profile similar, in regard to their head group and acyl chain specificity, and effect on the enzyme activities of phospholipases, to that of the PC-specific lipid transfer protein [8]. Though the primary structure of the PC-specific lipid transfer protein has been elucidated [9], the sequence or the structure which is responsible for the interaction with the substrate has not yet been identified.…”