DIRECT LIQUID-CHROMATOGRAPHIC SEPARATION OF ENANTIOMERS ON IMMOBILIZED PROTEIN STATIONARY PHASES .8. A COMPARISON OF A SERIES OF SORBENTS BASED ON BOVINE SERUM-ALBUMIN AND ITS FRAGMENTS

A mixture of three peptides (Mr 38 000), obtained by enzymatic cleavage of bovine serum albumin (BSA) was isolated, immobilized to silica and used as a chiral stationary phase in liquid chromatography. A comparison of sorbents containing these fragments and intact BSA, showed that the enantioselectivity is preserved for only a limited number of compounds. Under identical mobile phase conditions, retention on the columns based on BSA fragments was also much lower than on those containing intact BSA. The method used for immobilization has a great influence on the retentive and enantioselective properties of the sorbent obtained. When sorbents based on BSA entrapped in silica and 3-aminopropylsilica, by cross-linking with glutaraldehyde were compared under identical mobile phase conditions, the latter were generally found to give larger capacity factors and often also larger α values. These results indicate that the increased hydrophobicity, primarily caused by the aminopropyl groups, partly contributes to the overall retention and chiral discrimination process and that the situation may be different from that in a solution of the free protein. © 1990.