title: The ammonium sulfate inhibition of human angiogenin.
abstract: In this study, we investigate the inhibition of human angiogenin by ammonium sulfate. The inhibitory potency of ammonium sulfate for human angiogenin (IC50 = 123.5 ± 14.9 mm) is comparable to that previously reported for RNase A (119.0 ± 6.5 mm) and RNase 2 (95.7 ± 9.3 mm). However, analysis of two X-ray crystal structures of human angiogenin in complex with sulfate anions (in acidic and basic pH environments, respectively) indicates an entirely distinct mechanism of inhibition. While ammonium sulfate inhibits the ribonucleolytic activity of RNase A and RNase 2 by binding to the active site of these enzymes, sulfate anions bind only to peripheral substrate anion-binding subsites of human angiogenin, and not to the active site.
authors.affiliation: Department of Biochemistry and Biotechnology, University of Thessaly, Larissa, Greece.
authors.forename: Demetra S M
authors.initials: DS
authors.lastname: Chatzileontiadou
authors.affiliation: Institute of Biology, Medicinal Chemistry & Biotechnology, National Hellenic Research Foundation, Athens, Greece.
authors.forename: Vicky G
authors.initials: VG
authors.lastname: Tsirkone
authors.affiliation: Institute of Biology, Medicinal Chemistry & Biotechnology, National Hellenic Research Foundation, Athens, Greece.
authors.forename: Kyriaki
authors.initials: K
authors.lastname: Dossi
authors.affiliation: Department of Biochemistry and Biotechnology, University of Thessaly, Larissa, Greece.
authors.forename: Aikaterini G
authors.initials: AG
authors.lastname: Kassouni
authors.affiliation: Department of Biochemistry and Biotechnology, University of Thessaly, Larissa, Greece.
authors.forename: Panagiota G V
authors.initials: PG
authors.lastname: Liggri
authors.affiliation: Department of Biochemistry and Biotechnology, University of Thessaly, Larissa, Greece.
authors.forename: Anastassia L
authors.initials: AL
authors.lastname: Kantsadi
authors.affiliation: Department of Biochemistry and Biotechnology, University of Thessaly, Larissa, Greece.
authors.forename: George A
authors.initials: GA
authors.lastname: Stravodimos
authors.affiliation: Department of Biochemistry and Biotechnology, University of Thessaly, Larissa, Greece.
authors.forename: Nikolaos A A
authors.initials: NA
authors.lastname: Balatsos
authors.affiliation: Department of Biochemistry and Biotechnology, University of Thessaly, Larissa, Greece.
authors.forename: Vassiliki T
authors.initials: VT
authors.lastname: Skamnaki
authors.affiliation: Department of Biochemistry and Biotechnology, University of Thessaly, Larissa, Greece.
authors.forename: Demetres D
authors.initials: DD
authors.lastname: Leonidas
mesh_terms: D000645:Ammonium Sulfate / Q000737:chemistry* / Q000494:pharmacology; D018360:Crystallography, X-Ray; D004722:Endoribonucleases / Q000737:chemistry; D006801:Humans; D007700:Kinetics; D011487:Protein Conformation; D012259:Ribonuclease, Pancreatic / Q000037:antagonists & inhibitors / Q000737:chemistry*; D013379:Substrate Specificity
chemical_list: D004722:Endoribonucleases; C046366:angiogenin; C029494:ribonuclease U; D012259:Ribonuclease, Pancreatic; D000645:Ammonium Sulfate
keywords: X-ray crystallography; ammonium sulfate; angiogenin; expression and purification; molecular cloning; neovascularization