Amino acids are biologically important organic compounds composed of amine and carboxylic acid functional groups, along with a side-chain specific to each amino acid. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen, though other elements are found in the side-chains of certain amino acids. About 500 amino acids are known and can be classified in many ways.
In the form of proteins, amino acids comprise the second-largest component (water is the largest) of human muscles, cells and other tissues. Outside proteins, amino acids perform critical roles in processes such as neurotransmitter transport and biosynthesis.
9 proteinogenic amino acids are called “essential” for humans because they cannot be created by the human body and must be taken in as food. Others may be conditionally essential for certain ages or medical conditions. Because of their biological significance, amino acids are important in nutrition and are commonly used in nutritional supplements, fertilizers, and food technology.
Excerpt from: Wikipedia.
Amino acids are 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.
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.
Excerpt from: Paula’s Choice Website.