RESUMO
Individual protein domains and two domains in combination were prepared by enzymatic and chemical cleavage of turkey ovomucoid followed by isolation and purification by size-exclusion and ion-exchange chromatography. Silica bonded-phase HPLC columns were made from either whole or isolated domains of turkey ovomucoid. The protein columns were tested for chiral recognition by their abilities to resolve enantiomers among a wide range of racemates. The columns made from whole turkey ovomucoid displayed chiral activity toward many racemates, where as a combination of the first and second domain resolved only a selected number of aromatic weak bases. The first and second domains independently gave no appreciable chiral activity. The turkey ovomucoid third domain exhibited enantioselective protein binding for fused-ring aromatic weak acids. Glycosylation of the third domain did not affect chiral recognition. Titration of the third domain with model compounds in conjunction with NMR measurements enabled the identification of the amino acids responsible for binding. Molecular modeling of the ligand-protein complexation provided insights into the ability of a protein surface to discriminate enantiomers on the basis of multiple intermolecular interactions.
