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S Abrahamsson

Publications and source records attributed to S Abrahamsson.

15 recordsLinked to original sources
PubMed1977

Cholesteryl sulphate and phosphate in the solid state and in aqueous systems.

Cholesteryl sodium sulphate (CS) crystallizes as the dihydrate, the crystal structure of which is known. On heating the dihydrate, solid state phase transitions are observed at 65 degrees C and 95 degrees C and melting occurs at 165 degrees C. The structure of the high temperature phase has not been determined. Cholesteryl dihydrogen phosphate (CP) is not isostructural with any phases of CS. It undergoes a phase transition at 50 degrees C and melts at 190 degrees C. In systems with water CS is unstable whereas it was possible to determine the phase diagram of CP. In most of the composition range a crystalline hydrate is in equilibrium with a gel-phase. The latter has remarkable properties in that lamellar order exists with the 46 A lipid bilayer interleaved with water layers up to 1000 A. The monofilm behaviour of CS and CP at different pH levels is also reported.

Cholesterol↗
PubMed1977

The crystal structure of cholesteryl 17-bromoheptadecanoate.

Crystals of cholesteryl-17-bromoheptadecanoate (C44H77BrO2) are monoclinic (P21) with a = 7.663(2), b = 10.311(5), c = 55.96(2) A and beta = 103.10(3 degrees). These are two molecules in the asymmetric unit which have different conformations of the cholesterol side chain and about the ester bond. The molecules pack with regions of only steroid skeleta alternating with regions of hydrocarbon chains. Due to the packing requirements of the skeleta the carbon chains are forced into a hybrid type packing which contains features of the earlier known O perpendicular and T parallel subcells. The subcell (HS1) is orthorhombic with as = 10.3, bs = 7.5 and cs = 2.54 A. The molecular packing is such that the omega-bromine atoms do not continue the trans-carbon chains but adopt a gauche conformation.

Cholesterol Esters↗