51871-39-7 GHTST L-Tyrosine, N-(N-(N-(N-(5-oxo-L-prolyl)-L-histidyl)-L-tryptophyl)-L-seryl)-, methyl ester Pglu-his-trp-ser-tyr-ome Pyroglutamyl-histidyl-tryptophyl-seryl-tyrosyl methyl ester