Positional isotope exchange analysis of the uridine-diphosphoglucose pyrophosphorylase reaction

Conference · Thu May 01 04:00:00 EDT 1986 · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)

OSTI ID:6936913

Hester, L; Hilscher, L; Raushel, F M

The enzyme uridine-diphosphoglucose pyrophosphorylase catalyzes the reversible formation of pyrophosphate and UDP-glucose from UTP and glc-1P. The positional isotope exchange reaction was measured using oxygen-18 labelled UTP. The synthesis of (..beta..-/sup 18/O/sub 2/, ..beta gamma..-/sup 18/O, ..gamma..-/sup 18/O/sub 3/)UTP was accomplished by the coupled activities of carbamate kinase, nucleoside diphosphate kinase, and nucleoside monophosphate kinase. The exchange of an oxygen-18 from a ..beta..-nonbridge position of the labelled UTP to the ..cap alpha beta..-bridge position was measured with /sup 31/P NMR. The ratio of the rate of net substrate turnover and the positional isotope exchange rate was measured as a function of the initial glc-1P concentration. This ratio was found to increase with an increasing concentration of glc-1P. The intercept at low glc-1P was found to be 1.2 and the slope was 4.5 mM/sup -1/. These results have been interpreted to mean that this enzyme has an ordered addition of substrates. The lower limit for the release of pyrophosphate from E-UDPG-PP/sub i/ relative to V/sub 2/ is 1.2. The rate constant for the release of UTP from E-UTP relative to V/sub 1/ is 9.

• Research Organization: Texas A and M Univ., College Station
• OSTI ID: 6936913
• Report Number(s): CONF-8606151-
• Conference Information: Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Journal Volume: 45:6
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
550600 -- Medicine
59 BASIC BIOLOGICAL SCIENCES
62 RADIOLOGY AND NUCLEAR MEDICINE
AZINES
ENZYME ACTIVITY
ENZYMES
EVEN-EVEN NUCLEI
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
ISOTOPE APPLICATIONS
ISOTOPES
ISOTOPIC EXCHANGE
LIGHT NUCLEI
MAGNETIC RESONANCE
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
NUCLEI
NUCLEOSIDES
NUCLEOTIDES
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXYGEN 18
OXYGEN COMPOUNDS
OXYGEN ISOTOPES
PHOSPHORUS 31
PHOSPHORUS COMPOUNDS
PHOSPHORUS ISOTOPES
PHOSPHORUS-GROUP TRANSFERASES
PHOSPHOTRANSFERASES
PYRIMIDINES
PYROPHOSPHATES
RESONANCE
RIBOSIDES
SPECTRA
STABLE ISOTOPES
TRACER TECHNIQUES
TRANSFERASES
URACILS
URIDINE