Me. Hodsdon et al., H-1, C-13 AND N-15 ASSIGNMENTS AND CHEMICAL SHIFT-DERIVED SECONDARY STRUCTURE OF INTESTINAL FATTY-ACID-BINDING PROTEIN, Journal of biomolecular NMR, 6(2), 1995, pp. 198-210
Sequence-specific H-1, C-13 and N-15 resonance assignments have been e
stablished for rat intestinal fatty acid-binding protein complexed wit
h palmitate (15.4 kDa) at pH 7.2 and 37 degrees C. The resonance assig
nment strategy involved the concerted use of seven 3D triple-resonance
experiments (CC-TOCSY, HCCH-TOCSY, HNCO, HNCA, N-15-TOCSY-HMQC, HCACO
and HCA(CO)N). A central feature of this strategy was the concurrent
assignment of both backbone and side-chain aliphatic atoms, which was
critical for overcoming ambiguities in the assignment process. The CC-
TOCSY experiment provided the unambiguous links between the side-chain
spin systems observed in HCCH-TOCSY and the backbone correlations obs
erved in the other experiments. Assignments were established for 124 o
f the 131 residues, although 6 of the 124 had missing amide H-1 resona
nces, presumably due to rapid-exchange with solvent under these experi
mental conditions. The assignment database was used to determine the s
olution secondary structure of the complex, based on chemical shift in
dices for the H-1(alpha), C-13(alpha), C-13(beta), and (CO)-C-13 atoms
. Overall, the secondary structure agreed well with that determined by
X-ray crystallography [Sacchettini et al. (1989) J. Mol. Biol., 208,
327-339], although minor differences were observed at the edges of sec
ondary structure elements.