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

The backbone dynamics of bovine heart fatty acid binding protein (H-FABP) and porcine ileal lipid binding protein (ILBP) were studied by 15N NMR relaxation (T1 and T2) and steady state heteronuclear 15N1H NOE measurements. The microdynamic parameters characterizing the backbone mobility were determined using the ‘model-free’ approach. For H-FABP, the non-terminal backbone amide groups display a rather compact protein structure of low flexibility. 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 µsec-msec time range for ILBP compared to H-FABP. These results suggest significant differences in the conformational stability for these two structurally highly homologous members of the fatty acid binding protein family.