title: Stereochemistry of metal ion coordination to the terminal thiophosphoryl group of adenosine 5'-O-(3-thiotriphosphate) at the active site of pyruvate kinase.
abstract: Epimers of [gamma-17O]adenosine 5'-O-(3-thiotriphosphate) ([gamma-17O]ATP gamma S) have been used to determine the stereochemistry of Mn2+ coordination to the terminal thiophosphoryl group in complexes of pyruvate kinase, oxalate, ATP gamma S, and Mg2+, Zn2+, Co2+, or Cd2+. The complex of pyruvate kinase with oxalate and ATP binds 2 equiv of divalent cation per active site. The terminal phosphoryl group of ATP in this enzymic complex becomes a chiral center as a result of coordination to both divalent metal ions. Electron paramagnetic resonance (EPR) data for complexes of pyruvate kinase with Rp- or Sp-[gamma-17O]-ATP gamma S, [17O]oxalate, and mixtures of Mn2+ with Mg2+, Zn2+, or Co2+ show that Mn2+ binds selectively at the site defined by coordination to oxalate and the pro-R oxygen of the thiophosphoryl group of ATP gamma S. In mixtures containing Mn2+ and Cd2+ with Tl+ as the monovalent cation, two hybrid complexes form, enzyme-oxalate-MnII-ATP gamma S-CdII and enzyme-oxalate-CdII-ATP gamma S-MnII, as in the analogous complexes with ATP and K+ or Tl+ (Buchbinder, J. L., & Reed, G. H. (1990) Biochemistry 29, 1799-1806). In the enzyme-oxalate-MnII-ATP gamma S-CdII species, Mn2+ binds exclusively to the pro-R oxygen of the thiophosphoryl group. In the enzyme-oxalate-CdII-ATP gamma S-MnII species, Mn2+ binds to the pro-R oxygen (60%) and to the pro-S oxygen (40%).(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Institute for Enzyme Research, Graduate School, University of Wisconsin-Madison 53705.
authors.forename: J L
authors.initials: JL
authors.lastname: Buchbinder
authors.forename: J
authors.initials: J
authors.lastname: Baraniak
authors.forename: P A
authors.initials: PA
authors.lastname: Frey
authors.forename: G H
authors.initials: GH
authors.lastname: Reed
mesh_terms: D000255:Adenosine Triphosphate / Q000031:analogs & derivatives* / Q000737:chemistry; D001665:Binding Sites; D003035:Cobalt / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy; D008274:Magnesium / Q000737:chemistry; D008345:Manganese / Q000737:chemistry; D008958:Models, Molecular; D011770:Pyruvate Kinase / Q000737:chemistry*; D013873:Thionucleotides / Q000737:chemistry*; D015032:Zinc / Q000737:chemistry
chemical_list: D013873:Thionucleotides; C022571:adenosine 5'-O-(3-thiotriphosphate); D003035:Cobalt; D008345:Manganese; D000255:Adenosine Triphosphate; D011770:Pyruvate Kinase; D008274:Magnesium; D015032:Zinc