In the DPP-4/Diprotin A co-crystal structure (PDB ID 1nu8), the peptide bond between the second and third residues is not cleaved after formation of the tetrahedral intermediate, wherein the sidechain of the catalytic serine (Ser630) is covalently linked to the carbonyl carbon atom Pro2
It stimulates the pigment cells in your skin to produce more melanin, and this makes the skin look darker
It may take very little to go from the casual use of a substance to active addiction

Water, Methylpropanediol, Glycerin, Dimethicone, Titanium Dioxide, Niacinamide, Cyclopentasiloxane, Betaine, Polyglycerin-3, 1,2-Hexanediol, Sodium Acrylate/Sodium Acryloyldimethyl Taurate Copolymer, Sodium Polyacrylate, Ethylhexyl Stearate, Isohexadecane, Butylene Glycol, Panthenol, Dimethiconol, Dipropylene Glycol, Hydroxyacetophenone, Laminaria Japonica Extract, Eclipta Prostrata Leaf Extract, Polysorbate 80, Glutathione, Fragrance, Sorbitan Oleate, Triethoxycaprylylsilane, Trideceth-6, Hydrogenated Lecithin, Beta-Glucan, Squalane, Fructooligosaccharides, Hydrogenated Polyisobutene, Disodium EDTA, Argania Spinosa Kernel Oil, Isononyl Isononanoate, Polyglyceryl-10 Stearate, Ulmus Davidiana Root Extract, Panax Ginseng Root Extract, Amaranthus Caudatus Seed Extract, Cetearyl Alcohol, Stearic Acid, Butyrospermum Parkii (Shea) Butter, Polyglyceryl-2 Dipolyhydroxystearate, Hydrolyzed Hyaluronic Acid, Ficus Carica (Fig) Fruit Extract, Centella Asiatica Extract, Inulin Lauryl Carbamate, Glycyrrhiza Glabra (Licorice) Root Extract, Pearl Powder, Carbomer, Ceramide NP, Phenoxyethanol, Polysorbate 20, Disodium Stearoyl Glutamate, Lactobacillus/Rice Ferment, Ethylhexylglycerin, Palmitoyl Pentapeptide-4

doi: 10.3389/fnut.2024.1473648 Received 31 July 2024 Accepted 16 September 2024 Published 30 September 2024 Volume 11 - 2024 Edited by Ken Ng, The University of Melbourne, Australia Reviewed by Wentong Xue, China Agricultural University, China Peng Wu, First Affiliated Hospital of Zhengzhou University, China Kaijian Hou, Shantou University, China Updates Copyright 2024 Zou, Chen, Huang, Wang, Luo, Wang and Wang
68 (2), e12627