The 2D TOCSY-NOESY (TONO) experiment is an hybrid experiment
consisting of consecutive TOCSY and NOESY building blocks. In the
first step, magnetization is transferred between protons via scalar J coupling
and in the second step, such magnetization is propagated via NOE.
REQUIREMENTS
Easy implementation on AVANCE spectrometers.
VERSIONS
The basic pulse sequence of the TOCSY-NOESY experiment consists
of a conventional 2D TOCSY pulse sequence followed
by a NOESY building block
(
88ANG564
and
88MRC919
).
Modified sequences have been considered:
A related 2D TOCSY-ROESY experiment
(
88JMR401-77
,
88MRC919
, and
92JMR593-100
)
has been proposed by replacing the NOESY mixing time by a
ROESY
mixing time.
An alternative has been proposed in order to acquire the TOCSY and the
TONO data simultaneously
(
90JMR408-87
).
Application on small DNA oligomers has been reported
(
91JMR401-94
).
EXPERIMENTAL DETAILS
The 2D TOCSY-NOESY experiment can be recorded in routine/automation
modes. The most important parameter to consider is the length of the
the TOCSY and NOESY mixing periods. See 2D TOCSY
and 2D NOESY experiments for more details.
In the TOCSY-NOESY experiment, the two-step magnetization transfer
from a spin 1 (in F1) via spin 2 to a spin 3 (in F2) requires a J-coupling
between 1 and 2 and a NOE transfer between 2 and 3. However, the requeriments
for a transfer from spin 3 (in F1) via spin 2 to a spin 1 are different.
That means TONO spectra are asymmetrical with respect to the diagonal.
The 2D data matrices can be phase corrected to pure phase absorption line
shape, with the cross-peaks showing only in-phase multiplet patterns in
both dimensions. However, the coherence transfer during the TOCSY
spin-lock period is not limited to a single transfer step; depending on
the length of the mixing time multi-steps transfers can also be observed.
However, if the TOCSY mixing time is long enough, cross-peaks can arise
from several different pathways of magnetization transfer and, therefore,
the interpretation of the resulting spectrum will be more difficult.
