ИСТИНА

Glycopeptide antibiotics immobilized on silica are one of the effective class of the stationary phases for chiral recognition of the wide range of optical active compounds. Despite of slight differences between Vancomycin and Eremomycin only the last has an enantioselectivity for amino acid separation. It is interesting to find localization definition, which is responsible for this enantioselectivity. For this purpose, we have investigated Chlorine Eremomycin with the same position of chlorine as in Vancomycin and two amides – simplest small amide and bulky amide – Adamantyl derivative as chiral ligands immobilized on silica. It was shown that for amino acid enantiomer separation in the standard conditions (20% МеОН, 0,1 М NaH2PO4, pH – 4,5) the selectivity for amides selectors practically the same as for Eremomycin. Unexpectedly for the Chlorine Eremomycin molecule which structure closer for Vancomycin the enantioselectivity even growing. The resolution factor (Rs) for the most amino acids more than 1.5 in the different eluents. Investigations also demonstrate that: - it is possible to separate isomers in buffers without organic solvents; - it was finding the conditions (10% MeOH, 0,1% HClO4, pH 4.2), which gives more than 20% growing of enantioselectivity for aliphatic amino acids; - for the acidic amino acids the best selectivity occurs in phosphate buffer pH 3.6-4.5; - for the Phe and Trp the enantioselectivity growing in a row MeOH-EtOH-i-PrOH-n-PrOH from 1.1 to1.5 for Trp and from 1.4 to 2.0 for Phe; - it is possible to separate basic amino acids (His, Lys) enantiomers on Chlorine Eremomycin in eluents with pH more than 8.5. - only for aromatic amino acid the selectivity going down from 3,8 for Phe and 1,9 for Trp on Eremomycin to 1,4 and 1,1 on Chlorine Eremomycin. Obtained results demonstrate the high selectivity for separation of amino acids enantiomers on all new stationary phases based on Eremomycin and gives possibilities to reduce the area of localization for possible chiral recognition centers.