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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 acid group (which is in the deprotonated –COO − form under biological conditions), and an imidazole side chain (which is partially protonated), classifying it as a ...
In case of humans there are 9 EAAs: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. [1] EAAs are provided in both animal and plant-based food. The EAAs in plants vary greatly due to the vast variation in the plant world and, in general, plants have much lower content of proteins than animal ...
In plants, the shikimate pathway first leads to the formation of chorismate, which is the precursor of phenylalanine, tyrosine, and tryptophan. These aromatic amino acids are the precursors of many secondary metabolites, all essential to a plant's biological functions, such as the hormones salicylate and auxin. This pathway contains enzymes ...
This leader sequence is important for the regulation of histidine in E. coli. The His operon operates under a system of coordinated regulation where all the gene products will be repressed or depressed equally. The main factor in the repression or derepression of histidine synthesis is the concentration of histidine charged tRNAs.
[71] [72] For example, the heparin-binding protein Azurocidin is a member of the PA clan, but with a glycine in place of the nucleophile and a serine in place of the histidine. [73] Similarly, RHBDF1 is a homolog of the S54 family rhomboid proteases with an alanine in the place of the nucleophilic serine.
Within an ecological food chain, consumers are categorized into primary consumers, secondary consumers, and tertiary consumers. [3] Primary consumers are herbivores, feeding on plants or algae. Caterpillars, insects, grasshoppers, termites and hummingbirds are all examples of primary consumers because they only eat autotrophs (plants).
Food chain in a Swedish lake. Osprey feed on northern pike, which in turn feed on perch which eat bleak which eat crustaceans.. A food chain is a linear network of links in a food web, often starting with an autotroph (such as grass or algae), also called a producer, and typically ending at an apex predator (such as grizzly bears or killer whales), detritivore (such as earthworms and woodlice ...
In bacteria, HDH is a single chain polypeptide; in fungi it is the C-terminal domain of a multifunctional enzyme which catalyses three different steps of histidine biosynthesis; and in plants it is expressed as a nuclear encoded protein precursor which is exported to the chloroplast. [1] [2] [3]