title: Calculated background elimination in quantifying nitric-oxide synthase enzyme activity.
abstract: Measuring nitric-oxide synthase (NOS) activity by monitoring the conversion of L-arginine to L-citrulline is currently the standard assay for NOS activity. We describe a simple method of quantifying low values of NOS activity by removing the background mathematically. When performing NOS activity studies in samples with low protein amount (< 25 microg/microl), we encountered the problem of sample values that can hardly be differentiated from blank values probably originating from radioactive-labeled arginine in the final eluate. Our method determines mathematically these background values and may be an improvement of the citrulline assay.
authors.affiliation: Department of Gynecology and Obstetrics, Division of Gynecological Endocrinology and Reproductive Medicine, University Hospital Vienna, Waehringer Guertel 18-20 EBO5Q, A-1090, Vienna, Austria. felix.stonek@akh-wien.ac.at
authors.forename: F
authors.initials: F
authors.lastname: Stonek
authors.forename: W
authors.initials: W
authors.lastname: Tschugguel
authors.forename: J C
authors.initials: JC
authors.lastname: Huber
authors.forename: C
authors.initials: C
authors.lastname: Schneeberger
mesh_terms: D001120:Arginine / Q000737:chemistry; D001671:Biochemistry / Q000379:methods*; D002956:Citrulline / Q000737:chemistry; D006801:Humans; D008962:Models, Theoretical; D019001:Nitric Oxide Synthase / Q000096:biosynthesis* / Q000737:chemistry*; D013696:Temperature
chemical_list: D002956:Citrulline; D001120:Arginine; D019001:Nitric Oxide Synthase