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The distinction between essential and non-essential amino acids is somewhat unclear, as some amino acids can be produced from others. The sulfur-containing amino acids, methionine and homocysteine, can be converted into each other but neither can be synthesized de novo in humans. Likewise, cysteine can be made from homocysteine but cannot be ...
There are nine essential amino acids which humans must obtain from their diet in order to prevent protein-energy malnutrition and resulting death. They are phenylalanine, valine, threonine, tryptophan, methionine, leucine, isoleucine, lysine, and histidine. [2] [4] There has been debate as to whether there are 8 or 9 essential amino acids. [5]
Amino acids with the structure NH + 3 −CXY−CXY−CO − 2, such as β-alanine, a component of carnosine and a few other peptides, are β-amino acids. Ones with the structure NH + 3 −CXY−CXY−CXY−CO − 2 are γ-amino acids, and so on, where X and Y are two substituents (one of which is normally H). [7]
The side chains of the standard amino acids have a variety of chemical structures and properties, and it is the combined effect of all amino acids that determines its three-dimensional structure and chemical reactivity. [35] The amino acids in a polypeptide chain are linked by peptide bonds between amino and carboxyl
A healthy diet improves the physical and mental health of an organism. This requires ingestion and absorption of vitamins, minerals, essential amino acids from protein and essential fatty acids from fat-containing food. Carbohydrates, protein and fat play major roles in ensuring the quality of life, health and longevity of the organism. [10]
A complete protein source contains all the essential amino acids; an incomplete protein source lacks one or more of the essential amino acids. It is possible with protein combinations of two incomplete protein sources (e.g., rice and beans) to make a complete protein source, and characteristic combinations are the basis of distinct cultural ...
Amino acids contain both amino and carboxylic acid functional groups. (In biochemistry , the term amino acid is used when referring to those amino acids in which the amino and carboxylate functionalities are attached to the same carbon, plus proline which is not actually an amino acid).
Protein structure is the three-dimensional arrangement of atoms in an amino acid-chain molecule. Proteins are polymers – specifically polypeptides – formed from sequences of amino acids, which are the monomers of the polymer. A single amino acid monomer may also be called a residue, which indicates a