A comparative study of the backbone dynamics of two closely related lipid binding proteins: Bovine heart fatty acid binding protein and porcine ileallipid binding protein

The backbone dynamics of bovine heart fatty acid binding protein (H-FABP) a nd porcine ileal lipid binding protein (ILBP) were studied by N-15 NMR rela xation (T-1 and T-2) and steady state heteronuclear N-15 {H-1} NOE measurem ents. The microdynamic parameters characterizing the backbone mobility were determined using the 'model-free' approach. For H-FABP, the non-terminal b ackbone amide groups display a rather compact protein structure of low flex ibility. In contrast, for ILBP an increased number of backbone amide groups display unusually high internal mobility. Furthermore, the data indicate a higher degree of conformational exchange processes in the mu sec-msec time range for ILBP compared to H-FABP These results suggest significant differ ences in the conformational stability for these two structurally highly hom ologous members of the fatty acid binding protein family.