title: Kinetic analysis of cyclic CMP-specific and multifunctional phosphodiesterases by quantitative positive-ion fast-atom bombardment mass spectrometry.
abstract: Two enzymes, cyclic CMP-specific phosphodiesterase and multifunctional phosphodiesterase, are responsible for the hydrolysis of cytidine 3',5'-cyclic monophosphate in living cells. Quantitation of both enzymes has been carried out by positive-ion fast-atom bombardment mass spectrometric analysis of the enzyme incubates after termination of the reaction. The kinetic data obtained are in close agreement with parallel data obtained by the conventional radiometric assay. The extra facility of the mass spectrometry based assay to monitor several incubation components simultaneously has been exploited to study the concurrent hydrolysis of alternate cyclic nucleotide substrates and provides kinetic parameters of significance in interpreting substrate-enzyme interactions. This is extended by the use of collisionally-induced dissociation of the protonated molecules of the liberated products to identify the mononucleotide isomers resulting from the cyclic nucleotide hydrolysis.
authors.affiliation: Biochemistry Research Group, School of Biological Sciences, University of Wales Swansea, UK.
authors.forename: R P
authors.initials: RP
authors.lastname: Newton
authors.forename: M A
authors.initials: MA
authors.lastname: Bayliss
authors.forename: J A
authors.initials: JA
authors.lastname: Khan
authors.forename: A
authors.initials: A
authors.lastname: Bastani
authors.forename: A C
authors.initials: AC
authors.lastname: Wilkins
authors.forename: D E
authors.initials: DE
authors.lastname: Games
authors.forename: T J
authors.initials: TJ
authors.lastname: Walton
authors.forename: A G
authors.initials: AG
authors.lastname: Brenton
authors.forename: F M
authors.initials: FM
authors.lastname: Harris
mesh_terms: D063309:2',3'-Cyclic Nucleotide 3'-Phosphodiesterase; D000465:Algorithms; D000818:Animals; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006868:Hydrolysis; D007700:Kinetics; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D010727:Phosphoric Diester Hydrolases / Q000737:chemistry* / Q000378:metabolism; D051381:Rats; D016339:Spectrometry, Mass, Fast Atom Bombardment; D013379:Substrate Specificity
chemical_list: D004791:Enzyme Inhibitors; D010726:Phosphodiesterase Inhibitors; D010727:Phosphoric Diester Hydrolases; D063309:2',3'-Cyclic Nucleotide 3'-Phosphodiesterase; C571339:Cnp protein, rat