| Summary: | 碩士 === 國立中央大學 === 化學工程與材料工程學系 === 101 === Teriparatide, a peptide drug for treating to osteoporosis by once-daily injection, is the 1-34 segment of recombinant human parathyroid hormone. However, Teriparatide is proteolytically instable in human serum resulting in short circulation half-life (less than 1 hour). Therefore, conjugation with polyethylene glycol (PEGylation) to Teriparatide may shield it from proteolysis to prolong the circulation half-life. For the PEGylated Teriparatide, the positional isomers are usually formed with random PEGylation. We obtained the Nter-PEGylated and K13-PEGylated Teriparatide while the synthesis conditions using pH 6.0 and pH8.0 phosphate buffer, respectively. In this investigation, we intended to directly separate the isomers by tuning mobile phase pH in reversed-phase chromatography (RPC) operation. The results showed that the baseline separation of two isomers can be achieved by tuning the pH value of mobile phase from 7.0 to 9.0, and Nter-PEGylated Teriparatide is much retained in RPC. Form the solubility parameter measurement, we examined that the key factor for the separation of these two isomers is the polarity difference rather than hydrogen bonding or dispersion force. From the circular dichroism measurement, the K13- PEGylated Teriparatide with higher helixity shows less retained in RPC. The results are coherent with our previously proposed structure-retention relationships for peptide isomer retention prediction in RPC.
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