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SynopsisFormation of the antiparallel-chain @-sheet protein conformation is induced in in uitro human stratum corneum by three homologous organic sulfoxides known to enhance skin permeability: dimethylsulfoxide (MeZSO), hexylmethylsulfoxide (HxMeSO), and decylmethylsulfoxide (DecMeSO). MeZSO and HxMeSO apparently function by displacing water molecules bound to polar protein side-chains, whereas DecMeSO probably interacts hydrophobically with the protein. The conformational transition does not result from lipid removal. The @-sheet protein, most likely formed in normally a-helical portions of the intracellular keratin filaments, is reconverted to a-helix upon rehydration of the tissue. Though neat Me&O produces the most @-sheet of all treatments examined, the sequence of ability to promote @-sheet formation at the 1M level is HxMeSO > DecMeSO > MefiO. Spectroscopic evidence is presented regarding the dependence of @-sheet formation on sulfoxide concentration, treatment duration, pH, and tissue hydration. The relationship of this conformational change to the enhancement of skin permeability is briefly discussed. The result of sulfoxide treatment is different from results of sodium dodecylsulfate and heat treatments of stratum corneum.

Raman spectra (160-1700 cm-1) were recorded for aqueous solutions containing various ratios of nitrate to bismuth and also for a ( 03)3• 5H20-KN03 melt. Infrared spectra (400-1800 cm-1) were obtained for several of the solutions and the hydrate melt. The spectra are consistent with the presence of nitrate of C2v symmetry, and from the polarization of the highest frequency Raman line (at ca. 1500 cm-1), bidentate coordination is inferred. There is no evidence of nitrate bridging. The appearance of a polarized Raman band at ca. 235 cm-1, which is assigned to the symmetric bismuth-nitrate stretching motion, is evidence for covalency in the metal-ligand bond. Raman intensity measurements indicate the existence of stepwise complexes containing one through four nitrates per bismuth. In each of these species, water is also bound to bismuth, as is shown by a polarized band at ca. 370 cm-1, attributed to the symmetric bismuth-water stretching vibration.Bi-N08" frequency increases from 232 cm"1 in the concentrated aqueous solution to 239 cm"1 in the melt.

Raman spectra have been obtained of aqueous solutions containing B (0H)a-and various polyols, including 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, and 1,2,3-propanetriol. Several spectral features arise which can be explained only on the basis of the chelate formation originally postulated by Hermans; there is no evidence of polymerization in the concentrated solutions examined. Assignments are presented for the simplest five-membered (1,2-ethanediol) and six-membered (1,3-propanediol) borate chelates and comparisons made with related ring systems. Spectral changes caused by ring substitution are briefly discussed. il band assigned t o B-0 ring stretching provides the most reliable indication of ring size, having an average position of 766 cm-I for five-membered and ca. 720 cm-' for six-membered chelates. Through quantitative intensity measurements on the aqueous 1,2-ethanediol-B(OH)4-system, it is established that 1 : 1 and 2 : 1 (diol: boron) complexes exist in concentrated solution; a t 30°, the overall equilibrium molarity quotients are p1 = 1.8 =k 0.2 M-l and 02 = 0.65 =I= 0.15 M F 2 .

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