What are Combined Amino Acids?
Combined amino acids refer to amino acids that are bound together, most commonly through peptide bonds to form larger molecules like peptides and proteins. This contrasts with free amino acids, which exist independently in solution.
Within a protein, multiple amino acids are linked together by peptide bonds, forming a long chain. A peptide bond is created by a biochemical reaction that removes a water molecule as it joins the amino group of one amino acid to the carboxyl group of a neighboring amino acid. [Reference: A general description of peptide bonds]
This process of linking amino acids is crucial for protein synthesis, a fundamental biological process. The specific sequence and arrangement of amino acids determine the protein's structure and function.
Combined Amino Acids in Various Contexts
The term "combined amino acids" appears in various scientific contexts, highlighting the diverse ways amino acids can be linked:
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In biological systems: Combined amino acids are essential components of proteins and peptides, serving diverse functions within organisms. The relative proportions of different amino acids in combined form can vary significantly depending on the organism, tissue, and environmental conditions. For example, in deep Pacific Ocean waters, alanine comprises 60-70% of combined amino acids, while in surface waters this proportion is only around 30%. [Reference: Combined amino acids in Pacific Ocean waters]
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In environmental studies: Researchers study combined amino acids in the context of marine aerosols, investigating their transfer and transformation processes. The research looks at free (FAAs) and combined amino acids (CAAs) in sea spray aerosol particles. [Reference: Sea Spray Aerosol Chamber Study on Selective Transfer and ...]
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In nutritional research: Studies investigate the combined effects of amino acids with carbohydrates on muscle protein synthesis after exercise [Reference: Independent and combined effects of amino acids and glucose after ...] and the effects of combining amino acids with insulin to stimulate muscle protein synthesis (MiPS). [Reference: High Insulin Combined With Essential Amino Acids Stimulates ...] Additionally, research explores combining different plant proteins to optimize amino acid profiles for specific nutritional goals. [Reference: Combining Plant Proteins to Achieve Amino Acid Profiles Adapted to ...]
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In water treatment: Combined amino acids (in the form of peptides and proteins) are examined for their contribution to chlorine demand and the formation of disinfection byproducts during water treatment. [Reference: Chlorination studies of free and combined amino acids]
Examples of Combined Amino Acids
- Proteins: Hemoglobin, insulin, collagen, and antibodies are all examples of proteins – long chains of combined amino acids.
- Peptides: Glutathione, a small peptide with antioxidant properties, consists of three combined amino acids.
- Other: Combined amino acids can also be found in other macromolecules like glycoproteins (proteins with attached carbohydrates).
