title: The complete microspeciation of ovothiol A disulfide: a hexabasic symmetric biomolecule.
abstract: The site-specific acid-base properties of ovothiol A disulfide (OvSSOv), the smallest hexabasic multifunctional biomolecule with complex interdependent moieties, were studied with (1)H NMR-pH and potentiometric titrations. The unprecedented complexity of the protonation microequilibria could be overcome by taking into account the mirror-image molecular symmetry, synthesizing and studying auxiliary model compounds and developing a custom-tailored evaluation method. The amino, imidazole, and carboxylate moieties are quantified in terms of 192 microscopic protonation constants and 64 microspecies, 96 and 36 of which are chemically different ones, respectively. Nine pairwise interactivity parameters also characterize the OvSSOv-proton system at the level of molecular subunits. These data allow understanding and influencing the co-dependent acid-base and redox properties of the highly complex OvSH-OvSSOv and related thiol-disulfide systems, which provide protection against oxidative stress. This work is the first complete microspeciation of a hexabasic molecule.
authors.affiliation: Department of Pharmaceutical Chemistry, Semmelweis University, Budapest, Hungary; Research Group of Drugs of Abuse and Doping Agents, Hungarian Academy of Sciences, H-1092, Budapest, Hőgyes E. u. 9, Hungary.
authors.forename: Arash
authors.initials: A
authors.lastname: Mirzahosseini
authors.affiliation: Department of Pharmaceutical Chemistry, Semmelweis University, Budapest, Hungary; Research Group of Drugs of Abuse and Doping Agents, Hungarian Academy of Sciences, H-1092, Budapest, Hőgyes E. u. 9, Hungary.
authors.forename: Gábor
authors.initials: G
authors.lastname: Orgován
authors.affiliation: Department of Pharmaceutical Chemistry, Semmelweis University, Budapest, Hungary; Research Group of Drugs of Abuse and Doping Agents, Hungarian Academy of Sciences, H-1092, Budapest, Hőgyes E. u. 9, Hungary.
authors.forename: Gergő
authors.initials: G
authors.lastname: Tóth
authors.affiliation: Department of Pharmaceutical Chemistry, Semmelweis University, Budapest, Hungary; Research Group of Drugs of Abuse and Doping Agents, Hungarian Academy of Sciences, H-1092, Budapest, Hőgyes E. u. 9, Hungary.
authors.forename: Sándor
authors.initials: S
authors.lastname: Hosztafi
authors.affiliation: Department of Pharmaceutical Chemistry, Semmelweis University, Budapest, Hungary; Research Group of Drugs of Abuse and Doping Agents, Hungarian Academy of Sciences, H-1092, Budapest, Hőgyes E. u. 9, Hungary. Electronic address: noszal.bela@pharma.semmelweis-univ.hu.
authors.forename: Béla
authors.initials: B
authors.lastname: Noszál
mesh_terms: D000143:Acids / Q000737:chemistry; D000468:Alkalies / Q000737:chemistry; D004220:Disulfides / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008762:Methylhistidines / Q000737:chemistry*; D011522:Protons
chemical_list: D000143:Acids; D000468:Alkalies; D004220:Disulfides; D008762:Methylhistidines; D011522:Protons; C061475:ovothiol A
keywords: Acidity; Antioxidants; Microspeciation; NMR spectroscopy; Ovothiol