Folic acid delivery by serum proteins: loading efficacy and protein morphology

The loading efficacy of folic acid with serum proteins human serum albumin (HSA), bovine serum albumin (BSA), and beta-lactoglobulin (-LG) was analyzed and the effect of acid conjugation on protein morphology was determined. Structural analysis showed that folic acid binds HSA, BSA, and -LG via hydrophilic, hydrophobic, and H-bonding contacts with BSA forming more stable conjugates than HSA and -LG. Molecular modeling showed the presence of several H-bonding systems, stabilizing acid-protein conjugates. Folic acid conjugation alters protein conformation by major alterations of -helix and -sheet. TEM images showed major protein morphological changes inducing protein aggregation upon acid interaction. The results show that serum proteins can deliver folic acid to target molecules.