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As a fuel, proteins provide as much energy density as carbohydrates: 17 kJ (4 kcal) per gram; in contrast, lipids provide 37 kJ (9 kcal) per gram. The most important aspect and defining characteristic of protein from a nutritional standpoint is its amino acid composition. [2] Proteins are polymer chains made of amino acids linked together by ...
Protein anabolism is the process by which proteins are formed from amino acids. It relies on five processes: amino acid synthesis, transcription, translation, post translational modifications, and protein folding. Proteins are made from amino acids. In humans, some amino acids can be synthesized using already existing intermediates. These amino ...
The words protein, polypeptide, and peptide are a little ambiguous and can overlap in meaning. Protein is generally used to refer to the complete biological molecule in a stable conformation, whereas peptide is generally reserved for a short amino acid oligomers often lacking a stable 3D structure. But the boundary between the two is not well ...
The foodstuffs listed for comparison show the essential amino acid content per unit of the total protein of the food, 100g of spinach, for example, only contains 2.9g of protein (6% Daily Value), and of that protein 1.36% is tryptophan. [2] [7] (note that the examples have not been corrected for digestibility)
[2] The chemical elements humans consume in the largest quantities are carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulphur, summarized as CHNOPS. The chemical compounds that humans consume in the largest quantities and provide bulk energy are classified as carbohydrates, proteins, and fats. Water must be also consumed in large ...
Proteins are very large molecules—macro-biopolymers—made from monomers called amino acids. An amino acid consists of an alpha carbon atom attached to an amino group, –NH 2 , a carboxylic acid group, –COOH (although these exist as –NH 3 + and –COO − under physiologic conditions), a simple hydrogen atom , and a side chain commonly ...
Fats are triglycerides, made of assorted fatty acid monomers bound to a glycerol backbone. Some fatty acids, but not all, are essential in the diet: they cannot be synthesized in the body. Protein molecules contain nitrogen atoms in addition to carbon, oxygen, and hydrogen. [11]
At the top level are all alpha proteins (domains consisting of alpha helices), all beta proteins (domains consisting of beta sheets), and mixed alpha helix/beta sheet proteins. While most proteins adopt a single stable fold, a few proteins can rapidly interconvert between one or more folds. These are referred to as metamorphic proteins. [5]