title: Arginine-specific mono(ADP-ribosyl)transferase activity on the surface of human polymorphonuclear neutrophil leucocytes.
abstract: An Arg-specific mono(ADP-ribosyl)transferase activity on the surface of human polymorphonuclear neutrophil leucocytes (PMNs) was confirmed by the use of diethylamino-(benzylidineamino)guanidine (DEA-BAG) as an ADP-ribose acceptor. Two separate HPLC systems were used to separate ADP-ribosyl-DEA-BAG from reaction mixtures, and its presence was confirmed by electrospray mass spectrometry. ADP-ribosyl-DEA-BAG was produced in the presence of PMNs, but not in their absence. Incubation of DEA-BAG with ADP-ribose (0.1-10 mM) did not yield ADP-ribosyl-DEA-BAG, which indicates that ADP-ribosyl-DEA-BAG formed in the presence of PMNs was not simply a product of a reaction between DEA-BAG and free ADP-ribose, due possibly to the hydrolysis of NAD+ by an NAD+ glycohydrolase. The assay of mono(ADP-ribosyl)transferase with agmatine as a substrate was modified for intact PMNs, and the activity was found to be approx. 50-fold lower than that in rabbit cardiac membranes. The Km of the enzyme for NAD+ was 100.1 30.4 microM and the Vmax 1.4 0.2 pmol of ADP-ribosylagmatine/h per 10(6) cells. The enzyme is likely to be linked to the cell surface via a glycosylphosphatidylinositol anchor, since incubation of intact PMNs with phosphoinositol-specific phospholipase C (PI-PLC) led to a 98% decrease in mono(ADP-ribosyl)transferase activity in the cells. Cell surface proteins were labelled after exposure of intact PMNs to [32P]NAD+. Their molecular masses were 79, 67, 46, 36 and 26 kDa. The time course for labelling was non-linear under these conditions over a period of 4 h. The labelled products were identified as mono(ADP-ribosyl)ated proteins by hydrolysis with snake venom phosphodiesterase to yield 5'-AMP.
authors.affiliation: Department of Clinical Pharmacology, Royal Postgraduate Medical School, London, U.K.
authors.forename: L E
authors.initials: LE
authors.lastname: Donnelly
authors.forename: N B
authors.initials: NB
authors.lastname: Rendell
authors.forename: S
authors.initials: S
authors.lastname: Murray
authors.forename: J R
authors.initials: JR
authors.lastname: Allport
authors.forename: G
authors.initials: G
authors.lastname: Lo
authors.forename: P
authors.initials: P
authors.lastname: Kefalas
authors.forename: G W
authors.initials: GW
authors.lastname: Taylor
authors.forename: J
authors.initials: J
authors.lastname: MacDermot
mesh_terms: D036002:ADP Ribose Transferases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D000818:Animals; D002462:Cell Membrane / Q000201:enzymology; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism; D008970:Molecular Weight; D009504:Neutrophils / Q000201:enzymology*; D011817:Rabbits
chemical_list: D008565:Membrane Proteins; D036002:ADP Ribose Transferases