Properties of Acid Phosphatase in Human Stratum corneum

Abstract

Sheets of stratum corneum were prepared by a trypsinization procedure from human skin samples, homogenized with a freeze press and then fractionated into a soluble fraction and a sediment by centrifugation at 50,000 g. Acid phosphatase (AcP) activity was found in both fractions but the bulk of the activity was detected in the supernatant. Highest activities were observed after treatment with Triton X-100. The bulk of the AcP activity remained bound to the pellet if suspension and fractionation of the homogenized stratum corneum were performed in acetate buffer in the range between pH 4.0–5.0, probably due to ionic or hydrophobic interactions. AcP activity was totally lost if homogenates or fractions were stored frozen at –20°C in buffers with pH values lower than 4.0. Triton X-100 extracts from whole skin, epidermis, stratum corneum, cultured skin fibroblasts and leukocytes were compared by isoelectric focusing. Extracts from whole skin, epidermis and stratum corneum yielded almost identical patterns with one main AcP activity band at pi of 5.65 whereas a second pronounced band from whole skin behaved similarly to one band from cultured skin fibroblasts and leukocytes (pI 6.1). The prominent band from extracts of stratum corneum and epidermis was not observed in extracts of skin fibroblasts and leukocytes. Hence we conclude that stratum corneum and epidermis contain a tissue-specific AcP.

EEMCO Guidance for the in vivo Assessment of Skin Surface pH

“…In addition to lipids, the lamellar bodies are enriched in certain hydrolytic enzymes, including acid phosphatase, proteases, a family of lipases (phospholipase A, sphingomyelinase, steroid sulfatase, acid lipase, among others) and a family of glycosidases [21][22][23]. Barrier formation requires the transformation of the initially secreted lipids (predominantly glucosylceramides, cholesterol and phospholipids) into a less polar mixture enriched in ceramides, cholesterol and free fatty acids.…”

Epidermal Enzymes: Their Role in Homeostasis and Their Relationships with Dermatoses

“…Gunaratne et al [11] effectively showed that a cytoplasmic tyrosine phosphatase can dephosphorylate the EGF receptor itself as well as other substrates. Moreover, a phosphatase acid activity has clearly been identified on the whole epidermis, the activity of which increases from the basal to the cornified layer [12]; therefore this activity increases with the degree of differentiation [13].…”

Evidence for the Existence of a Self-Regulated Enzymatic Process Within the Human Stratum Corneum –An Unexpected Role for Urocanic Acid

“…Hydrolytic enzymes such as phosphatase, which are stored in the lamellar bodies (pH 7) of stratum granulosum, are released to extracellular space during corni®cation. They are activated by acidic pH (Meyer et al, 1990). Numerous hydrolases such as proteases (chymotrypsin, trypsin, cathepsin, etc.…”