trans-Urocanic acid is a major epidermal chromophore for the immunosuppressive effects of UV radiation that is produced in mammalian stratum corneum by the action of histidine ammonialyase on L-histidine.{26632} It contributes to the acidification of the surface of the stratum corneum, and its function has been proposed as that of an endogenous sunscreen, endowing a low-level of protection (SPF ~ 1.5) against UV-induced DNA damage and excessive keratinocyte apoptosis.{26632} Upon UVB exposure, trans-urocanic acid is converted to the cis isomer, which is known to activate regulatory T cells.{26631}
产品描述
A major epidermal chromophore for the immunosuppressive effects of UV radiation that is produced in mammalian stratum corneum by the action of L-histidine ammonia lyase on histidine
