CHARACTERIZATION OF CARDIAC FATTY-ACID-BINDING PROTEIN FROM HUMAN PLACENTA - COMPARISON WITH PLACENTA HEPATIC TYPES

When a 10500OXg supernatant of human placenta was incubated with [1-C-14]oleate and subjected to Sephadex G-75 gel filtration and HPLC, two fatty-acid-binding protein (FABP) peaks were obtained. One of these, when further purified by carboxymethyl-cellulose, gave one 15.3-kDa FABP with pI 5.3. The other, when chromatographed on DEAE cellulose, separated into two 14.2-kDa FABP with pI 6.9 and 5.4. Purity of the proteins was checked by SDS/PAGE. Molecular mass, pI, immunochemical properties and amino acid compositions all indicated that 15.3-kDa FABP was of the cardiac type, whereas both 14.2-kDa FABP were of the hepatic type. Cardiac FABP did not cross-react with hepatic proteins. When tested for die acceptor/donor properties of these FABP, hepatic types were found to be better candidates than cardiac in uptaking fatty acids from liposomes. Cardiac FABP, on the other hand, acted in a more efficient way as a donor, indicating a distinct role of these proteins in human placenta, which furnishes a multiorgan system for the developing fetus.