Synopsis

The molecular organization of human stratum corneum (SC) is still poorly known, in spite of its importance for the understanding of its biological functions. By using ø synchrotron X-ray diffraction a d oriented samples, new basic features were revealed in the 2.5-to-125 A domain. The X-ray patterns were richer and more complex than previously published. Lipid extraction allows discrimination between the proteic or lipidic origin of the numerous arcs and rings observed. Concerning the proteins, we found that the keratin organization (or versus {3) in human stratum corneum depends on its origin and environment, contrary to the commonly accepted ot form for skin keratin. For common SC it would be close to {3, and for "callus " type it is or. An unknown {3-pleated sheet protein with an 9.4 • interchain distance was inferred from the diffraction data. Reticular distances of the lipidic lameliar organization were evidenced by small-angle diffraction (10-65 •). Wide angle diffraction (2.5-10 •) showed intermolecular distances of different species of lipids. Certain features of the X-ray diagrams can be assigned (i.e., cholesterol). Liposomes, which are made also of organized lipids, can be characterized by an X-ray diagram. This fact is important for cosmetic research, providing the possibility to study the interaction between the stratum corneum and liposomes. Some examples will be reported