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Protein is a nutrient needed by the human body for growth and maintenance. Aside from water, proteins are the most abundant kind of molecules in the body. Protein can be found in all cells of the body and is the major structural component of all cells in the body, especially muscle. This also includes body organs, hair and skin.
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 repeating unit of a polymer.
Hemoglobin's quaternary structure comes from its four subunits in roughly a tetrahedral arrangement. [43] In most vertebrates, the hemoglobin molecule is an assembly of four globular protein subunits. Each subunit is composed of a protein chain tightly associated with a non-protein prosthetic heme group.
Essential amino acid. An essential amino acid, or indispensable amino acid, is an amino acid that cannot be synthesized from scratch by the organism fast enough to supply its demand, and must therefore come from the diet. Of the 21 amino acids common to all life forms, the nine amino acids humans cannot synthesize are valine, isoleucine ...
Computational protein structure prediction of small protein structural domains [25] has also helped researchers to approach atomic-level resolution of protein structures. As of April 2024 [update] , the Protein Data Bank contains 181,018 X-ray, 19,809 EM and 12,697 NMR protein structures.
The quaternary structure refers to the number and arrangement of the protein subunits with respect to one another. [2] Examples of proteins with quaternary structure include hemoglobin, DNA polymerase, ribosomes, antibodies, and ion channels. Enzymes composed of subunits with diverse functions are sometimes called holoenzymes, in which some ...
Human nutrition deals with the provision of essential nutrients in food that are necessary to support human life and good health. [1] Poor nutrition is a chronic problem often linked to poverty, food security , or a poor understanding of nutritional requirements. [ 2 ]
In molecular biology, a protein domain is a region of a protein 's polypeptide chain that is self-stabilizing and that folds independently from the rest. Each domain forms a compact folded three-dimensional structure. Many proteins consist of several domains, and a domain may appear in a variety of different proteins.