For a GHKCu (coppercomplexed glycylhistidyllysine) solution prepared at 1 mg mL, how many insulinsyringe units (1 unit = 0.01 mL) should be drawn for a specific dose? GHK Cu Purepep Your body made this peptide every day until you turned 30. Then it stopped. GHK Cu (copper peptide) is a naturally occurring tripeptide discovered in 1973. At age 20, your plasma levels sit GHK Cu Peptides: Unlocking the Copper Peptide Revolution in Skin Care