Amino acids are nitrogen-containing molecules that serve as the building blocks for proteins. Every protein possesses a unique sequence of amino acids that determines its structure and function. Your body contains hundreds of thousands of different proteins, each of which performs a specific task. Proteins serve as enzymes, hormones, immune molecules, molecular transporters and structural components. Collagen, a structural protein, is one of the most abundant proteins in your body.
Form and Function
Connective tissue is the material that forms the structural framework for your organs, bones, eyes, tendons, cartilage, skin, blood vessels, lymphatics and muscles. Collagen is the chief protein in connective tissue. Collagen exists in different forms, depending on its location in your body. Although the same amino acids are utilized to synthesize all forms of collagen, the ultimate shape and function of the collagen molecule is determined by how it is modified during its production.
Collagen is manufactured by specialized cells called fibroblasts. These cells are capable of incorporating amino acids into the highly distinctive strands that constitute the basic unit of the collagen molecule. Dr. Elson Haas, author of "Staying Healthy with Nutrition," reports that glycine, lysine and proline are the primary amino acids found in collagen, accounting for at least 50 percent of its amino acid content. As they are secreted by fibroblasts, collagen strands undergo binding, twisting, cross-linking, folding and layering to produce the final product.
Amino Acid Modification
Glycine accounts for one-third of the amino acids in the collagen molecule. Lysine and proline, which constitute another one-sixth of the collagen strand's amino acid content, are converted to hydroxylysine and hydroxyproline before they are incorporated into the strand. The enzyme that performs these conversions requires vitamin C as a cofactor. Hence, a deficiency of vitamin C inhibits the conversion of proline and lysine and interferes with the production of collagen. This interference is the basis for scurvy, a nutritional disease that leads to the breakdown of your skin and mucous membranes.
Amino Acid Sources
Glycine can be synthesized in your body from choline, a B vitamin, or from the amino acids threonine or serine. Similarly, proline can be produced in your cells from other amino acids, namely glutamine and ornithine. Lysine is an essential amino acid, meaning it cannot be synthesized in your body. It must be acquired from dietary sources, such as meats, fish, dairy products, legumes, wheat germ, fruits and vegetables. A well-balanced diet supplies sufficient protein to fulfill your needs for lysine, proline, glycine and any other amino acids needed for collagen synthesis. Amino acid supplements are also commercially available.