th  - 1988 - 51st ENC Conference

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NMR CHARACTERIZATION OF THE
GLYPHOSATE-SHIKIMATE-3-PHOSPHATE- ENZYME
DEAD-END COMPLEX.
Stephen Castellino, Gregory C. Leo', R. Douglas Sammons and James A.
Sikorski
Monsanto Agriculture Company, a Unit of Monsanto Company, .800 N.
Lindbergh Boulevard, St. Louis, MO 63167
The herbicidal dead-end ternary complex of glyphosate with EPSP syn-
thase (EC 2.5.1.19 from E. toll) and the substrate shikimate-3-phosphate
(S3P) has been characterized by 13C,1S N and 31p .NMR. The enzyme bound
glyphosate and S3P have unique chemical shifts. The phosphorus chemical
shifts observed for glyphosate are shown to be dependent upon the position
of the phosphorus atom relative to the free electrons of the nitrogen atom.
77 I
PULSE SHAPING AND SELECTIVE
EXCITATION : THE EFFECT OF SCALAR COUPLING
R. Bazzo0, J. Boyd and N. Soffe, Dept. of Biochemistry,
University of Oxford, Oxford, UK.
Recently, a good deal of interest has centred around the
use of shaped pulses for a variety of ID and 2D experiments.
Long low power rectansular pulses or waWeforms shaped like
Hyperbolic Secants, Sine: func.tions, Oaussian or half-
Gaussian functions have been used in these experiments.
For very seleotlve pulses the averase r.f. power is
adjusted to be the same order of masnltude as the J
couplin S. A theoretical description suitable for sele,=:tive
shaped pulses is siven, which includes the effect of the
scalar couplin 6. The excitation profile for the different
coherence components of the irradiated spin will be shown
for the commonly used shaped waveforms.
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