Synthesis and Self-organizing Properties of Iminodiacetic Phospholipids and Their Role in Noncolvant Enzyme Immobilization on Organized Assemblies.
NAVAL RESEARCH LAB WASHINGTON DC
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Diacetylenic phospholipids with metal chelating iminodiacetic acid IDA headgroup, R-O-CH2-CHOR-CH-OPOHO- OCH2CH-n-NCH2COOH2 where R palmitoyl or tricosa-lO,12-diynoyl and n 1-3, have been synthesized to explore their technical utility. The lipids homogeneity was confirmed by 1H and 13C NMR spectrometry. The microstructure formation properties of the lipids were studied by Langmuir film balance technique and transmission electron microscopy TEM. Synergistic influence of copper ions, ionic strength and pH of the dispersion medium, and length of the ethyleneoxy spacer in the headgroup caused the formation of ribbons and tubules. Increasingly, racemic diacetylenic phospholipids upon binding with copper produced ribbons and tubules when di- and tri-ethylenoxy spacer was inserted to separate phosphate and IDA moieties. In fully formed tubules, helical striations of uniform handedness were observed. Mixture of metal chelating lipids with diacetylenic phosphatidyicholine produced vesicles. To these vesicles and enzyme bovine carbonic anhydrase II EC 188.8.131.52 was non-covalently linked with the aid of copper ion. An affinity between copper-IDA complex and histidines available on enzyme surface facilitated this binding without affecting enzyme activity. Polymerized vesicles showed improved stability and sustained activity of enzymes.
- Inorganic Chemistry
- Organic Chemistry
- Metallurgy and Metallography