SYNTHESIS OF A SELENOMETHIONINE PEPTIDE AND A PRELIMINARY-STUDY OF TRANSPORT INTO ESCHERICHIA-COLI MONITORED BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

The tripeptide Gly-SeMet-Gly has been synthesized by a combination of solution and solid-phase methods. Increase in weight of the resin was very nearly theoretical, and purification was straightforward. Its abs orption was compared to that of the corresponding peptide, Gly-Met-Gly , in E. coli using HPLC ion-exchange separation and fluorometric deter mination of the disappearance of peptides in the culture medium and th e appearance of methionine and selenomethionine in the same culture me dium. As E. coli are not known to possess extracellular peptidases, an d in fact have been shown to possess transport systems for peptides, t his absorption is interpreted as transport of the peptide through the cell wall and membrane into the cytoplasm, endohydrolysis of the pepti de, and efflux of the peptides' amino acids. Uptake of both peptides w as approximately equal, but was slowed when both peptides were present simultaneously. (C) Munksgaard 1995.