“…For example, the structures of plasma retinol‐binding protein [6, 7]and epididymal retinoic acid binding protein [8]revealed buried retinoid species; the mouse major urinary protein a thiazoline derivative [9]; bilin‐binding protein a biliverdin molecule [10]; odorant‐binding protein an unidentified ligand, possibly a pyrazine derivative [11]; and for nitrophorin 1 a heme, bound through a histidine ligand to the protein [12]. There is evidence that bovine BLG binds a wide range of ligands, including fatty acids [13–23], retinol and retinol derivatives [20–27], porphyrin species [27, 28], assorted aromatic molecules [23, 29–32]and alkanone species [33, 34]. Despite many studies of ligand binding, there is, however, no unequivocal evidence as to where ligands, especially fatty‐acid type molecules, bind.…”