title: Inhibition of yeast growth by molybdenum-hydroxylamido complexes correlates with their presence in media at differing pH values.
abstract: The effects of Mo-hydroxylamido complexes on cell growth were determined in Saccharomyces cerevisiae to investigate the biological effects of four different Mo complexes as a function of pH. Studies with yeast, an eukaryotic cell, are particularly suited to examine growth at different pH values because this organism grows well from pH 3 to 6.5. Studies can therefore be performed both in the presence of intact complexes and when the complexes have hydrolyzed to ligand and free metal ion. One of the complexes we examined was structurally characterized by X-ray crystallography. Yeast growth was inhibited in media solutions containing added Mo-dialkylhydroxylamido complexes at pH 3-7. When combining the yeast growth studies with a systematic study of the Mo-hydroxylamido complexes' stability as a function of pH and an examination of their speciation in yeast media, the effects of intact complexes can be distinguished from that of ligand and metal. This is possible because different effects are observed with complex present than when ligand or metal alone is present. At pH 3, the growth inhibition is attributed to the forms of molybdate ion that exist in solution because most of the complexes have hydrolyzed to oxomolybdate and ligand. The monoalkylhydroxylamine ligand inhibited yeast growth at pH 5, 6 and 7, while the dialkylhydroxylamine ligands had little effect on yeast growth. Growth inhibition of the Mo-dialkylhydroxylamido complexes is observed when a complex exists in the media. A complex that is inert to ligand exchange is not effective even at pH 3 where other Mo-hydroxylamido complexes show growth inhibition as molybdate. These results show that the formation of some Mo complexes can protect yeast from the growth inhibition observed when either the ligand or Mo salt alone are present.
authors.affiliation: Department of Chemistry, Colorado State University, Fort Collins, CO 80523-1872, USA. crans@lamar.colostate.edu
authors.forename: Debbie C
authors.initials: DC
authors.lastname: Crans
authors.forename: Jason J
authors.initials: JJ
authors.lastname: Smee
authors.forename: Edita G
authors.initials: EG
authors.lastname: Gaidamauskiene
authors.forename: Oren P
authors.initials: OP
authors.lastname: Anderson
authors.forename: Susie M
authors.initials: SM
authors.lastname: Miller
authors.forename: Wenzheng
authors.initials: W
authors.lastname: Jin
authors.forename: Ernestas
authors.initials: E
authors.lastname: Gaidamauskas
authors.forename: Etienne
authors.initials: E
authors.lastname: Crubellier
authors.forename: Rose
authors.initials: R
authors.lastname: Grainda
authors.forename: Lai-Har
authors.initials: LH
authors.lastname: Chi
authors.forename: Gail R
authors.initials: GR
authors.lastname: Willsky
mesh_terms: D018360:Crystallography, X-Ray; D003470:Culture Media; D004563:Electrochemistry; D006863:Hydrogen-Ion Concentration; D006898:Hydroxylamines / Q000737:chemistry / Q000494:pharmacology*; D007700:Kinetics; D008958:Models, Molecular; D008968:Molecular Conformation; D008982:Molybdenum / Q000494:pharmacology*; D009942:Organometallic Compounds / Q000737:chemistry / Q000494:pharmacology; D012441:Saccharomyces cerevisiae / Q000187:drug effects* / Q000254:growth & development
chemical_list: D003470:Culture Media; D006898:Hydroxylamines; D009942:Organometallic Compounds; D008982:Molybdenum