Figure 7.

Species distribution simulated for natural moisturizing factor (NMF), 0.9 µM Cu²⁺ ions, and different concentrations of GHK, at pH 7.4 (representing the possible conditions in wounds). The lowest concentration of GHK (0.6 µM) is equal to the concentrations found in human plasma. Higher concentrations (6 and 60 µM) of GHK may occur in wounds and/or after application of cosmetics or other products with GHK as the active substance. The protonation constants and stability constants for Cu(II) complexes were taken from the literature [47,48] and this paper. The conditional constant for the ternary complexes formation of Cu(GHK) with carboxylates (68 M⁻¹) [20] was also included in calculations. Concentrations taken for calculations are 43 mM serine, 30 mM glycine, 23 mM pyroglutamic acid, 18 mM alanine, 14 mM lactic acid, and 14 mM cis-UCA [11,12]. All ternary complexes of Cu(GHK) with aforementioned compounds with carboxylic groups were combined in the “Cu(GHK)(carboxylates)”. Only the species exceeding 1% of all Cu(II) species are shown for clarity.