Positional isotope exchange studies on enzyme using NMR spectroscopy

Thesis/Dissertation · Thu Jan 01 04:00:00 EST 1987

OSTI ID:5347674

Matsunaga, T O

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
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AMINO ACIDS
ATP
AZOLES
CARBOXYLIC ACIDS
CREATINE
CREATININE
ENZYMES
EVEN-EVEN NUCLEI
HETEROCYCLIC COMPOUNDS
IMIDAZOLES
IMINES
ISOTOPES
ISOTOPIC EXCHANGE
LIGHT NUCLEI
MAGNETIC RESONANCE
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
NUCLEI
NUCLEOTIDES
ODD-EVEN NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXYGEN 18
OXYGEN COMPOUNDS
OXYGEN ISOTOPES
PHOSPHORUS 31
PHOSPHORUS COMPOUNDS
PHOSPHORUS ISOTOPES
PHOSPHORUS-GROUP TRANSFERASES
PHOSPHOTRANSFERASES
PYROPHOSPHATES
RESONANCE
SPECTRA
STABLE ISOTOPES
TRANSFERASES