title: Hydrolysis of sphingosylphosphocholine by neutral sphingomyelinases.
abstract: Sphingosylphosphocholine (SPC), the N-deacylated form of sphingomyelin (SM), is a naturally occurring lipid mediator. However, little is known about the metabolism of SPC. We here report an in vitro assay system for SPC-phospholipase C (PLC). Using this assay system, we demonstrated that nSMase1 and nSMase2, human neutral sphingomyelinases (SMases), are capable of hydrolyzing SPC efficiently under detergent-free conditions. Bacterial and plasmodial neutral SMases also showed SPC-PLC activity. The substrate specificity of neutral SMases that hydrolyze SM, SPC, and monoradyl glycerophosphocholine, but not diradyl glycerophosphocholine, suggested that a hydrogen-bond donor at the C-2 or sn-2 position in the substrate is required for recognition by the enzymes.
authors.affiliation: Department of Biochemistry and Cell Biology, National Institute of Infectious Diseases, 1-23-1, Toyama, Shinjuku-ku, Tokyo 162-8640, Japan.
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Miura
authors.forename: Eriko
authors.initials: E
authors.lastname: Gotoh
authors.forename: Futoshi
authors.initials: F
authors.lastname: Nara
authors.forename: Masahiro
authors.initials: M
authors.lastname: Nishijima
authors.forename: Kentaro
authors.initials: K
authors.lastname: Hanada
mesh_terms: D002460:Cell Line; D006801:Humans; D006868:Hydrolysis; D007668:Kidney; D007700:Kinetics; D008969:Molecular Sequence Data; D010743:Phospholipids / Q000378:metabolism; D010767:Phosphorylcholine / Q000031:analogs & derivatives* / Q000378:metabolism*; D013108:Sphingomyelin Phosphodiesterase / Q000378:metabolism*; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000378:metabolism*; D013379:Substrate Specificity; D010738:Type C Phospholipases / Q000378:metabolism
chemical_list: D010743:Phospholipids; C005356:sphingosine phosphorylcholine; D010767:Phosphorylcholine; D010738:Type C Phospholipases; C491484:SMPD3 protein, human; D013108:Sphingomyelin Phosphodiesterase; D013110:Sphingosine