Polypeptides are chains of amino acids linked by peptide bonds and can vary in length and composition. Here are some examples of polypeptides, both naturally occurring and synthetically produced:
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Insulin: A well-known hormone that regulates glucose levels in the blood. It consists of two polypeptide chains (A and B chains) linked by disulfide bonds.
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Glucagon: Another hormone that works in opposition to insulin to increase blood glucose levels. It is also a polypeptide, composed of 29 amino acids.
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Hemoglobin: A protein in red blood cells that carries oxygen. It is made up of four polypeptide chains (two alpha and two beta chains).
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Collagen: The most abundant protein in mammals, forming the structural framework of tissues such as skin, tendons, and bones. It consists of three polypeptide chains twisted into a triple helix.
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Antibodies (Immunoglobulins): Proteins produced by the immune system that bind to antigens (foreign substances). Each antibody is made up of a combination of heavy and light polypeptide chains.
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Cytochrome c: A polypeptide involved in the electron transport chain in mitochondria, facilitating cellular respiration.
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Myelin Basic Protein (MBP): A significant component of the myelin sheath in the nervous system, essential for proper nerve function.
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Enkephalins: Naturally occurring pentapeptides that function as neurotransmitters and play a role in pain regulation and mood.
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Glutathione: A tripeptide composed of glutamine, cysteine, and glycine, functioning as an antioxidant and in various metabolic processes.
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Synthetic Polypeptides: Researchers can design and synthesize polypeptides for various applications, including drug delivery systems, biomaterials, and vaccines.
These examples highlight the diversity of polypeptides and their critical roles in biological systems.