Fundamental constituents of all proteins found in the body, such as: alanine, arginine, asparagine, aspartic acid, cysteine, cystine, glutamic acid, glutamine, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, and valine. Some of these amino acids can be synthesized by the body; others, the essential amino acids must be obtained from protein in the diet. In skin-care products, these types of ingredients act primarily as water-binding agents, and some have antioxidant properties and wound-healing abilities as well. However, these substances cannot affect, change, or rebuild wrinkles. Whether the protein in a skin-care product is derived from an animal or a plant, the skin can’t tell the difference. See natural moisturizing factor (NMF) , protein