Structural and biochemical properties of bidentate tetraaquarhodium(III) complexes of inorganic pyrophosphate and adenosine 5'-diphosphate
The structural and biochemical properties of the alpha,beta-bidentate tetraaquarhodium(III) complexes of inorganic pyrophosphate (Rh(H/sub 2/O)4PP) and adenosine diphosphate (Rh(H/sub 2/O)4ADP) are examined. These Rh(III) complexes are exchange-inert analogues of the corresponding physiologically important MgIIPP and MgIIADP complexes. The crystal structure of (Rh(H/sub 2/O)4H/sub 2/P/sub 2/O/sub 7/)+Cl- shows that the six-membered chelate ring adopts a twist-boat conformation with an unusually high puckering amplitude of 0.756 (3) A. The Rh coordination distances average 2.02 (1) A, while the bridge P-O bonds are virtually equal in length. All 10 protons of the complex participate in hydrogen bonding. There are two intramolecular hydrogen bonds between the phosphate oxygen atoms and the axially coordinated water molecules. The Rh(H/sub 2/O)4PP complex was found to be a substrate for yeast inorganic pyrophosphatase, with Ki = 0.063 (7) mM and Vm = 500 (100) min-1. The two screw sense isomers of Rh(H/sub 2/O)4ADP were prepared from (Rp)-(alpha-16O,18O)ADP and assigned configuration on the basis of the magnitude of their /sup 31/P NMR isotopic chemical shifts. The Rh(H/sub 2/O)4ADP complex binds a number of kinases as tightly as MgADP. Arginine kinase and creatine kinase were shown to bind the delta Rh(H/sub 2/O)4ADP isomer 7 and 45 times tighter, respectively, than the lambda isomer. The reactivity of Rh(H/sub 2/O)4PP with pyrophosphatase is comparable to that of Cr(H/sub 2/O)4PP, and the binding affinities of the Rh(H/sub 2/O)4ADP screw sense isomers for kinases are also comparable to those observed for the corresponding Cr(H/sub 2/O)4ADP screw sense isomers.
- Research Organization:
- Univ. of Maryland, College Park
- OSTI ID:
- 6074412
- Journal Information:
- Biochemistry; (United States), Vol. 26:7
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ADP
CHEMICAL PROPERTIES
MOLECULAR STRUCTURE
PYROPHOSPHATES
BIOCHEMICAL REACTION KINETICS
CHEMICAL SHIFT
COMPLEXES
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
OXYGEN ISOTOPES
PHOSPHORUS 31
PHOSPHOTRANSFERASES
RHODIUM
ELEMENTS
ENZYMES
ISOTOPES
KINETICS
LIGHT NUCLEI
MAGNETIC RESONANCE
METALS
NUCLEI
NUCLEOTIDES
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PHOSPHORUS COMPOUNDS
PHOSPHORUS ISOTOPES
PHOSPHORUS-GROUP TRANSFERASES
PLATINUM METALS
REACTION KINETICS
RESONANCE
SPECTRA
STABLE ISOTOPES
TRANSFERASES
TRANSITION ELEMENTS
550201* - Biochemistry- Tracer Techniques