Positional isotope exchange studies on enzyme using NMR spectroscopy
The isotopically enriched compounds, /sup 18/O-..beta..,..gamma..-ATP and /sup 18/O bridge-labeled pyrophosphate, synthesized previously in this laboratory, were used to investigate and measure the exchange vs. turnover of substrates and products from their central complexes in four selected enzyme systems. Using hi-field /sup 31/P NMR, we were able to differentiate between /sup 18/O labeled in the bridge vs. the non-bridge positions by virtue of the isotope shift upon the phosphorus nuclei. The bridge to non-bridge scrambling of the label was quantitated and the exchange vs. turnover ratios under a variety of conditions was determined. Using the substrate inhibitor carboxycreatinine, PIX experiments with /sup 18/O-..beta..,..gamma..-ATP and creatine kinase were conducted. It was shown that carboxycreatinine and creatine kinase promoted exchange of the /sup 18/O label as determined by NMR. We have concluded that carboxycreatinine is either a substrate that catalyzes very slow turnover or it catalyzes exchange by a dissociative (SN/sub 1//sub P/) type of mechanism
- Research Organization:
- California Univ., San Francisco (USA)
- OSTI ID:
- 5347674
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
PHOSPHOTRANSFERASES
ISOTOPIC EXCHANGE
NMR SPECTRA
ATP
CREATINE
CREATININE
NUCLEAR MAGNETIC RESONANCE
OXYGEN 18
PHOSPHORUS 31
PYROPHOSPHATES
AMINO ACIDS
AZOLES
CARBOXYLIC ACIDS
ENZYMES
EVEN-EVEN NUCLEI
HETEROCYCLIC COMPOUNDS
IMIDAZOLES
IMINES
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
NUCLEI
NUCLEOTIDES
ODD-EVEN NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXYGEN COMPOUNDS
OXYGEN ISOTOPES
PHOSPHORUS COMPOUNDS
PHOSPHORUS ISOTOPES
PHOSPHORUS-GROUP TRANSFERASES
RESONANCE
SPECTRA
STABLE ISOTOPES
TRANSFERASES
550201* - Biochemistry- Tracer Techniques