The skin of atopic dermatitis patients contains a novel enzyme, glucosylceramide sphingomyelin deacylase, which cleaves the N-acyl linkage of sphingomyelin and glucosylceramide.

摘要: We have demonstrated previously that there is an abnormal expression of sphingomyelin (SM) deacylase in the epidermis patients with atopic dermatitis (ADe). In present study, we prepared N -[palmitic acid-1- 14 C]SM and C]glucosylceramide (GCer) to use as substrates quantified SM activity by detecting release [ C]palmitic acid extracts stratum corneum or ADe patients. studies using [palmitic a substrate, pH dependency catalytic peak at 5.0 was found. Preparative SDS/PAGE extract revealed molecular mass 40000Da, which consistent its apparent 42000Da estimated gel-filtration analysis extracts. Analytical isoelectric focusing (IEF) chromatography pI values deacylase, β-glucocerebrosidase (GlcCDase), sphingomyelinase (SMase) ceramidase were 4.2, 7.4, 7.0 5.7, respectively. enzymic pI-4.2 partially purified IEF, had no detectable contamination ceramidase, GlcCDase SMase, radio-TLC radiolabelled sphingosylphosphocholine [1- enzymically liberated from [choline-methyl- -[palmitoyl-1- C]GCer, respectively, used substrates. Further protein able hydrolyse GCer, but not C]ceramide. These results indicate hitherto undiscovered epidermal enzyme, termed here glucosylceramide expressed skin patients, plays important role ceramide deficiency (including acylceramides) corneum.