Goates C Y, Knutson K
Department of Pharmaceutics and Pharmaceutical Chemistry/CCCD, University of Utah, Salt Lake City 84108.
Biochim Biophys Acta. 1993 Dec 12;1153(2):289-98. doi: 10.1016/0005-2736(93)90418-y.
Stratum corneum protein biochemical and biophysical structural contributions to the barrier properties of human epidermis were determined in the presence of the reducing agent dithiothreitol (DTT). Mannitol and sucrose permeation through human epidermis in the presence of 0 to 50 mM DTT in PBS (pH 7.4) was measured in symmetric, side-by-side diffusion cells (32 degrees C). DTT enhancement ratios, KP(DTT)/KP(PBS), ranging from 1.6 to 32, were dependent on skin donor and DTT concentrations. DTT did not alter stratum corneum uptake of mannitol or sucrose nor mannitol solubility in DTT/PBS solutions. Stratum corneum biophysical structure was ascertained by FTIR in solvent replacement experiments. DTT-induced protein conformational alterations were apparent in the emergence of an Amide I band near 1615 cm-1, which is generally associated with beta-sheet-like conformers. Therefore, DTT alters stratum corneum biophysical structure through interactions with proteins. After exposure of stratum corneum protein sheets to DTT/PBS solutions, the free thiol concentration increased from < 1 nmol SH/mg protein sheet to approx. 130 nmol/mg. The enhanced permeation which increased with increasing concentrations of DTT, was associated with diffusion mechanisms involving the cornified cells of the stratum corneum. These results indicate that corneocyte protein integrity does contribute to barrier function of the skin and influences the transport of polar solutes.
在还原剂二硫苏糖醇（DTT）存在的情况下，测定了角质层蛋白质对人类表皮屏障特性的生化和生物物理结构贡献。在对称的并排扩散池中（32℃），测量了在含有0至50 mM DTT的PBS（pH 7.4）中甘露醇和蔗糖透过人类表皮的情况。DTT增强率，即KP（DTT）/KP（PBS），范围为1.6至32，取决于皮肤供体和DTT浓度。DTT不会改变角质层对甘露醇或蔗糖的摄取，也不会改变甘露醇在DTT/PBS溶液中的溶解度。在溶剂置换实验中，通过傅里叶变换红外光谱（FTIR）确定角质层的生物物理结构。在1615 cm-1附近出现酰胺I带，这通常与β-折叠样构象体相关，表明DTT诱导的蛋白质构象改变很明显。因此，DTT通过与蛋白质的相互作用改变角质层的生物物理结构。将角质层蛋白质片暴露于DTT/PBS溶液后，游离巯基浓度从<1 nmol SH/mg蛋白质片增加到约130 nmol/mg。随着DTT浓度增加而增强的渗透与涉及角质层角质形成细胞的扩散机制有关。这些结果表明，角质形成细胞蛋白质的完整性确实有助于皮肤的屏障功能，并影响极性溶质的转运。
