Tripeptide epimers

Griehl, C. and Merkel, S., Synthesis and separation of pprotected tripeptide epimers by RP-HPLC, Inti. J. Peptide Protein Res., 45, 217, 1995. 

In a similar fashion, the retention behavior of 23 tripeptide epimers (with the basic structure Z-Ala-X-Val-OMe, where X is either the d or l form of the inserted amino acid) was studied on a C g column (A = 220 nm) using a series of isocratic methanol/water mobile phases [471]. The k values for all the lll and ldl forms and the resulting a values are tabulated for each epimer. Reasonable elution times were achieved, with mobile phases ranging fixim 60% to 80% methanol. The LDL-epimers were consistently more retained than the LLL-epimers. The authors attribute this to a larger surface area presented to the packing material in the ldl conformation. 

Twenty-five sets of benzyloxycarbonyl-glycine-X-Y-OMe epimers were chosen to study the racemization process that occurs during peptide synthesis [470]. These tripeptides were resolved on a 40°C Cjg column (A = 245 nm) using a number of isocratic methanol/water mobile phases. The inserted amino acid residues, X and Y, included combinations of alanine, valine, leucine, isoleucine, and phenylalanine. Mobile phase compositions ranged from 45% to 65% methanol (analyte dependent), capacity factors from 3 to 14, and a values fix)m 1.11 to 1.39. 

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