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Ecto‐diadenosine 5′,5‴‐P 1 ,P 4 ‐tetraphosphate (Ap 4 A)‐hydrolase is expressed as an ectoenzyme in a variety of mammalian and human cells and adds ne
Author(s) -
Drygalski Annette Von,
Ogilvie Adaling
Publication year - 2000
Publication title -
biofactors
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.204
H-Index - 94
eISSN - 1872-8081
pISSN - 0951-6433
DOI - 10.1002/biof.5520110304
Subject(s) - hydrolase , chemistry , extracellular , enzyme , intracellular , mesangium , biochemistry , cleavage (geology) , phosphatidylinositol , biology , kidney , endocrinology , signal transduction , paleontology , fracture (geology) , glomerulonephritis
Abstract Ap 4 A and other dinucleotides participate in the regulation of hemostasis and blood pressure control. With the exception of two previously reported surface anchored ectoAp 4 A‐hydrolases on bovine aortic endothelial and chromaffine cells, all Ap 4 A‐hydrolases reported are intracellular or freely soluble. We demonstrated that ectoAp 4 A‐hydrolases are present on a broad variety of cell types of different species: rat mesangial, bovine corneal epithelial, human Hep‐G2 and peridontal cells. Ectoenzyme properties were evaluated on rat mesangium cells. Chromatography of purified plasma membranes on Sephacel 300 resulted in enrichment of ectoAp 4 A‐hydrolase and in separation from ectoATPase. In contrast to ATPase, Ap 4 A‐hydrolase was stable at room temperature. EctoAp 4 A‐hydrolase also recognized ATP as substrate, and therefore is not highly specific. The molecular weight was 180 kD. Unlike ectoAMPase ectoAp 4 A‐hydrolase was not attached via a glycosyl‐phosphatidylinositol (GPI)‐moiety. Concentrations of PI‐PLC 10–100‐fold higher than effective for ectoAMPase cleavage (10–100 mU/ml) plus extensively extended incubation times up to eight hours did not result in cleavage of ectoAp 4 A‐hydrolase. The enzyme ectoAp 4 A‐hydrolase might presage a direction for pharmaceutical manipulation in the control of blood pressure and hemostasis.