Solution structure of fatty acid-binding protein from human brain.

Human brain-type fatty acid-binding protein (B-FABP) has been recombinantly expressed in Escherichia coli both unlabelled and 15N-enriched for structure investigation in solution using high-resolution NMR spectroscopy. The sequential assignments of the 1H and 15N resonances were achieved by applying multidimensional homo- and heteronuclear NMR experiments. The ensemble of the 20 final energy-minimized structures, representing human B-FABP in solution, have been calculated based on a total of 2490 meaningful distance constraints. The overall B-FABP structure exhibits the typical backbone conformation described for other members of the FABP family, consisting often antiparallel beta-strands (betaA to betaJ) that form two almost orthogonal beta-sheets, a helix-turn-helix motif that closes the beta-barrel on one side, and a short N-terminal helical loop. A comparison with the crystal structure of the same protein complexed with docosahexaenoic acid reveals only minor differences in both secondary structure and overall topology. Moreover, the NMR data indicate a close structural relationship between human B-FABP and heart-type FABP with respect to fatty acid binding inside the protein cavity.