Peptides are fundamental molecules found throughout living organisms, composed of linked building blocks called amino acids. They are widespread in biological systems and participate in a vast array of functions. Peptides serve as messengers and regulators, influencing various biological activities at a molecular level.
What Are Peptides?
Peptides are short chains of amino acids connected by specific chemical bonds. Amino acids are the basic units that make up both peptides and larger molecules called proteins. Peptides are generally defined as chains containing fewer than 50 amino acids, whereas proteins typically consist of 50 or more.
The linkage between amino acids in a peptide chain is known as a peptide bond, or amide bond. This bond forms when the carboxyl group of one amino acid reacts with the amino group of another, releasing a molecule of water in a process called dehydration synthesis. Peptide bonds are rigid and planar due to their partial double-bond character, which influences the overall shape and stability of the molecule. These bonds are stable under normal physiological conditions, contributing to their integrity.
Peptides Naturally in Your Body
The human body naturally produces thousands of different peptides, each with specific roles in maintaining health and regulating biological processes. These endogenous peptides act as signaling molecules, hormones, neurotransmitters, and antimicrobial agents, influencing everything from metabolism to immune responses. They are also involved in cell communication and gene expression.
Insulin is a well-known peptide hormone that regulates blood sugar levels. Produced by beta cells in the pancreas, insulin promotes the uptake of glucose from the blood into cells for energy or storage. High concentrations of insulin also inhibit glucose production by the liver.
Oxytocin, a peptide hormone, is produced in the hypothalamus and released by the pituitary gland. It plays a role in social bonding, reproduction, childbirth by stimulating uterine contractions, and milk ejection during breastfeeding.
Endorphins are peptides produced in the brain and adrenal medulla that function as natural painkillers. They block the perception of pain and contribute to feelings of well-being, often released during physical exercise or moments of pleasure.
Glucagon-like peptide-1 (GLP-1) is a peptide hormone produced in the gut in response to food consumption. GLP-1 encourages the release of insulin from the pancreas, helping to lower blood sugar levels. It also increases feelings of fullness by acting on appetite centers in the brain and slowing stomach emptying.
Peptides in Health and Wellness Products
Beyond their natural roles, peptides are increasingly utilized in various health and wellness products, including pharmaceuticals, dietary supplements, and cosmetics. These exogenous peptides are either sourced from natural materials or synthetically manufactured to deliver specific therapeutic or beneficial effects. Their smaller size compared to proteins can allow for easier absorption into the body.
In pharmaceuticals, peptides are developed as therapeutic agents for a range of conditions. Over 100 peptide drugs are approved in the U.S. for treating diseases such as type 2 diabetes, cancer, and HIV. For example, GLP-1 receptor agonists like semaglutide are synthetic peptides used to manage type 2 diabetes and obesity by mimicking natural GLP-1 to enhance insulin secretion and suppress appetite. Therapeutic peptides are valued for their high specificity to targets and lower toxicity, as they naturally degrade into amino acids in the body.
Dietary supplements often feature peptides, with collagen peptides being a common example. Collagen, a protein that provides structure to skin, bones, and connective tissues, is broken down into smaller peptides for easier absorption when consumed. These collagen peptides are thought to improve skin hydration and elasticity, and potentially alleviate joint pain. While research is ongoing, these supplements aim to provide the building blocks or signals for the body to support its own collagen production.
Cosmetic products incorporate peptides for their anti-aging benefits. Signal peptides stimulate fibroblasts in the skin to increase collagen and elastin production, which helps reduce wrinkles and improve skin firmness. Carrier peptides enhance the delivery of trace elements essential for skin repair and collagen synthesis. Other types work to slow the breakdown of existing collagen and elastin, preserving skin structure and elasticity.