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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, leucine, methionine ...
Lysine (symbol Lys or K) [2] is an α-amino acid that is a precursor to many proteins.It contains an α-amino group (which is in the protonated −NH + 3 form when dissolved in water), an α-carboxylic acid group (which is in the deprotonated −COO − form when dissolved in water), and a side chain lysyl ((CH 2) 4 NH 2), classifying it as a basic, charged (at physiological pH), aliphatic ...
Amino acid. Structure of a typical L -alpha-amino acid in the "neutral" form. Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. [1] Although over 500 amino acids exist in nature, by far the most important are the 22 α-amino acids incorporated into proteins. [2]
Phenylalanine is an essential amino acid that most of us get more than enough of through protein sources in our everyday diets, whether we eat mostly animal-derived, plant-based, or a mix of both.
The amino acids that an organism cannot synthesize on its own are referred to as essential amino acids. Key enzymes that synthesize certain amino acids are not present in animals—such as aspartokinase , which catalyses the first step in the synthesis of lysine , methionine , and threonine from aspartate .
Protein primary structure is the linear sequence of amino acids in a peptide or protein. [1] By convention, the primary structure of a protein is reported starting from the amino -terminal (N) end to the carboxyl -terminal (C) end. Protein biosynthesis is most commonly performed by ribosomes in cells.
A protein contact map represents the distance between all possible amino acid residue pairs of a three-dimensional protein structure using a binary two-dimensional matrix. For two residues and , the element of the matrix is 1 if the two residues are closer than a predetermined threshold, and 0 otherwise. Various contact definitions have been ...
Histidine. Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Histidine (symbol His or H) [2] is an essential amino acid that is used in the biosynthesis of proteins. It contains an α-amino group (which is in the protonated –NH 3+ form under biological conditions), a carboxylic ...