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1999 (1)
1996 (1)
1Author    Janina Kuczera3, TeresaE. Krai3, Marian Podolakb, Stanislaw Przestalski3Requires cookie*
 Title    A Joint Effect of Cationic and Anionic Amphiphilic Compounds on the Desorption of Calcium Ions from Lecithin Liposome Membranes  
 Abstract    The aim of the work was to determine the synergism and antagonism of mixtures of the cationic amphiphilic compounds: N-benzyl-N,N-dimethyl-N-tetradecylammonium chloride (BD TA), N-benzyl-N,N-dimethyl-N-dodecylammonium chloride (B D D A), N-methyl-N-te-tradecyl-morpholinium bromide (M TM), N,N,N-trimethyl-N-tetradecylammonium bromide (TM TA) and those of tripropyltin chloride in a mixture with amphiphilic anionic compounds (a homologous series of sodium alkylsulfonates with n = 2, 4, 6, 8, 10, 12 and 14 alkyl carbon atoms) in the process of calcium ion desorption from liposome lecithin membranes. Radioac­ tive labels and spin labels were used in the investigations. All compounds studied caused an increase in the kinetic rate constant of calcium ion desorption from liposome membranes with increasing concentration. In case of mixtures containing cationic and anionic compounds both synergism and antagonism were observed. It was shown that the regulatory effect depended on the properties of both cationic and anionic compounds. A mixture of the most effective cationic compound (BD TA) with each of the anionic compounds decreased the effect. Mixtures of the remaining ammonium com­ pounds with sodium alkylsulfonates produced both synergism and antagonism. Anionic com­ pounds with short chains increased, and with longer chains decreased efficiency, while com­ pounds with comparable chains caused totally blocked desorption. A mixture of an organometallic compound having three short chains with anionic compounds gave a reversed effect: short-chain compounds caused a decreased and those with long-chains -increased efficiency of tripropyltin chloride. Studies with spin labels supported the conclusion that the most important factor responsi­ ble for the regulatory effect is the molecular shape of the complexes formed in a mixture of both groups of compounds -a factor that determines membrane packing density 
  Reference    Z. Naturforsch. 54c, 429 (1999); received November 23 1998/February 12 1999 
  Published    1999 
  Keywords    Ca2+ Desorption, Liposomes, Amphiphiles, Organometallic Compounds, Regulatory Effect 
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 TEI-XML for    default:Reihe_C/54/ZNC-1999-54c-0429.pdf 
 Identifier    ZNC-1999-54c-0429 
 Volume    54 
2Author    WilhelmV. Dahlhoffd, Karin Radkowskia, Ingo Dierkingb, Peter ZugenmaierbRequires cookie*
 Title    Amphiphilic Carbohydrate-Based Mesogens, 12 [1] High-Yield Synthesis of Mesogenic l-O-Alkanoyl-D/L-Xylitols  
 Abstract    The equilibrium mixture of 1,2:3,4-and l,3:2,4-di-0-ethylboranediyl-D /L-xylitols 1 and 1' obtained on reaction o f three equivalents of xylitol with two equivalents of triethylboroxin, reacts with alkanoyl chlorides (heptanoyl-dodecanoyl) to give equilibrium mixtures of the O-ethylboranediyl protected l-O-alkanoyl-D.L-xylitols 2,2' after vacuum distillation. Depro­ tection of the latter affords the title amphiphilic esters 3 which melt to give the smectic A liquid-crystalline phase. 
  Reference    Z. Naturforsch. 51b, 1229—1234 (1996); received April 26 1996 
  Published    1996 
  Keywords    Carbohydrates, Amphiphiles, Liquid Crystals (Smectic), 1-0-A lkanoyl-D, L-X ylitols, X-Ray 
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 TEI-XML for    default:Reihe_B/51/ZNB-1996-51b-1229.pdf 
 Identifier    ZNB-1996-51b-1229 
 Volume    51