Amino acid sequence and some ligand binding properties of fatty acid-binding protein from bovine brain

A fatty acid-binding protein (FABP) from the cytosol of bovine brain was purified by Sephadex G-75 filtration and electrofocusing. The purified protein migrated as a single protein band in 15% polyacrylamide gel electrophoresis with an apparent molecular mass of 14.7 kDa. To ascertain that the purified protein was a FABP, it was submitted to fatty acid-binding tests. Oleic and palmitic acids bound to brain FABP but this was not the case for palmitoyl CoA. By Scatchard analysis the ligand binding values were: Kd = 0.28 microM, Bmax (mol/mol) = 0.6 for oleic acid and Kd = 0.8 microM, Bmax (mol/mol) = 2.1 for palmitic acid. The complete amino acid sequence of the brain FABP was determined and a microheterogeneity was observed. Sequence comparison with other FABPs of known sequence and the observed microheterogeneity demonstrated the presence in brain of several homologous FABPs closely related to heart FABP.