title: Chemical aspects of hydrogen sulfide measurements in physiological samples.
abstract: BACKGROUND
  Owing to recent discoveries of many hydrogen sulfide-mediated physiological processes, sulfide biology is in the focus of scientific research. However, the promiscuous chemical properties of sulfide pose complications for biological studies, which led to accumulation of controversial observations in the literature.
  
  
  METHODS
  We intend to provide an overview of fundamental thermodynamic and kinetic features of sulfide redox- and coordination-chemical reactions and protonation equilibria in relation to its biological functions. In light of these chemical properties we review the strengths and limitations of the most commonly used sulfide detection methods and recently developed fluorescent probes. We also give a personal perspective on blood and tissue sulfide measurements based on proposed biomolecule-sulfide interactions and point out important chemical aspects of handling sulfide reagent solutions.
  
  
  CONCLUSIONS
  The diverse chemistries of sulfide detection methods resulted in orders of magnitude differences in measured physiological sulfide levels. Investigations that were aimed to dissect the underlying molecular reasons responsible for these controversies made the important recognition that there are large sulfide reserves in biological systems. These sulfide pools are tightly regulated in a dynamic manner and they are likely to play a major role in regulation of endogenous-sulfide-mediated biological functions and avoiding toxic side effects.
  
  
  CONCLUSIONS
  Working with sulfide is challenging, because it requires considerable amounts of chemical knowledge to adequately handle reagent sulfide solutions and interpret biological observations. Therefore, we propose that a rigorous chemical approach could aid the reconciliation of the increasing number of controversies in sulfide biology. This article is part of a Special Issue entitled Current methods to study reactive oxygen species - pros and cons and biophysics of membrane proteins. Guest Editor: Christine Winterbourn.
authors.affiliation: Department of Molecular Immunology and Toxicology, National Institute of Oncology, Ráth György utca 7-9, Budapest 1122, Hungary. Electronic address: peter.nagy@oncol.hu.
authors.forename: Péter
authors.initials: P
authors.lastname: Nagy
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Pálinkás
authors.forename: Attila
authors.initials: A
authors.lastname: Nagy
authors.forename: Barna
authors.initials: B
authors.lastname: Budai
authors.forename: Imre
authors.initials: I
authors.lastname: Tóth
authors.forename: Anita
authors.initials: A
authors.lastname: Vasas
mesh_terms: D000818:Animals; D002468:Cell Physiological Phenomena; D005456:Fluorescent Dyes; D006801:Humans; D006862:Hydrogen Sulfide / Q000032:analysis*
chemical_list: D005456:Fluorescent Dyes; D006862:Hydrogen Sulfide
keywords: 3-mercaptopyruvate sulfurtransferase; 3MST; 4-(2-hydroxyethyl)-1-piperazineethane-sulfonic acid; 5,5-dithiobis-(2-nitrobenzoic acid); Blood sulfide pool; CBS; CCO; CSE; Coordination chemistry; Cys; DTNB; DTPA; DTT; GC; GSH; HEPES; HSOH; Hydrogen sulfide; MB; MBB; PBS; Protonation equilibria; ROS; RSOH; RSSH; Redox chemistry; SDB; TRIS; Tissue sulfide measurement; cystathionine beta-synthase; cystathionine gamma-lyase; cytochrome c oxidase; d,l-dithiotreitol; diethylenetriamine-pentaacetic-acid; gas chromatography; glutathione; l-cysteine; methylene blue method; monobromobimane method; persulfide; phosphate buffered saline; reactive oxygen species; sulfenic acid; sulfenic acid derivative; sulfide dibimane; tris(hydroxymethyl)aminomethane