Assignment of exchangeable imino and amino
proton and nitrogen resonances
-
2D 1H-15N HMQC/HSQC
experiment
(
93JMRA241-102
). A long-range
optimized Fast-HSQC experiment has been reported to correlate the N3 of cytosines
with the intrabase trans H42 proton via the large 3JNH
(
99JB173-15
).
-
Imino and amino proton resonances can be assigned from observation of intraresidue
and interstrand NOEs detected in
2D NOESY and/or in
3D (1H,15N,1H)
NOESY-HMQC (
92JB301
), NOESY-HSQC
(
93JMRB317-102
and
HSQC-NOESY
(
95JACS11043
)
experiments recorded in H2O.
-
Some pyrimidine-specific experiments have been described
to link aromatic to imino/amino hydrogens:
2D H(NCCC)H and 3D H(NCC)CH
experiments (
95JB427
and
96JACS689
).
2D H5(C5C4N)H experiments (
99JMR430-139
)
-
A related HCCNH-TOCSY approach (
96JB83
and
96JACS689
)
has been proposed to achieve unambiguous assignment of the exhangeable
imino proton resonances to the nonexchangeable purine H8 and pyrimidine
H6 protons. Some examples are the 2D H(CCN)H, 3D H(CC)NH and
3D HC(CN)H
experiments. Similar results have been reported using the reverse pathway
(2D H(NC)-TOCSY-(C)H (
96JB153
and
96JACS5316
).
