Effect of transition metals on recovery from plasma of the growth-modulating tripeptide glycylhistidyllysine

Abstract Isolation and purifications of growth-modulating peptides from biological sources is often accompanied by excessive losses of bioactive material. During the isolation of a growth-modulating tripeptide glycylhistidyllysine (GHL) from human plasma, copper and iron were found to co-isolate with the peptide. Studies with [ 3 H]GHL demonstrated that these metals interfere at several steps of the procedure for the isolation of GHL from plasma (gel filtration chromatography, high-pressure silica-gel). Removal of these metals with an insoluble chelating resin (Cellex 100) enhanced recover of [ 3 H]GHL from plasma 8-fold. These results suggest that removal of transition metals may aid in the recovery of peptides which are difficult to isolate from biological sources.