Crystalline cylindrical structures of Na(+)-bound dimyristoylphosphatidylglycerol as revealed by microcalorimetry and electron microscopy.
Multilamellar vesicles of dimyristoylphosphatidylglycerol (DMPG) in an aqueous medium of 1 M NaCl at pH 7.0 converted to defined cylindrical structures of crystalline phase, on annealing of 5 degrees C of a gel phase temperature. The new crystalline phase transformed into the liquid crystal phase at a transition point (44.2 degrees C) nearly the same as that of the protonated DMPG, but with a transition enthalpy (19.2 kcal/mol) larger than that of the Ca(2+)-bound DMPG of much higher transition temperature. Electron microscopic observations revealed that a set of outer membranes (8-10 lamellae) separated from the MLV grows into helical structures and, finally, into the crystalline cylindrical structures with an increase in annealing time.
Department of Biochemistry, Faculty of Science, Okayama University of Science, Japan.
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Kodama
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Miyata
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Yokoyama
D002151:Calorimetry; D003461:Crystallography; D008854:Microscopy, Electron; D010715:Phosphatidylglycerols / Q000737:chemistry*; D012965:Sodium Chloride; D013696:Temperature; D013816:Thermodynamics
D010715:Phosphatidylglycerols; D012965:Sodium Chloride; C002773:dimyristoylphosphatidylglycerol