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Threonine (symbol Thr or T) [2] is an amino acid that is used in the biosynthesis of proteins.It contains an α-amino group (which is in the protonated −NH + 3 form when dissolved in water), a carboxyl group (which is in the deprotonated −COO − form when dissolved in water), and a side chain containing a hydroxyl group, making it a polar, uncharged amino acid.
Threonine proteases use the amino acid threonine as their catalytic nucleophile. Unlike cysteine and serine, threonine is a secondary hydroxyl (i.e. has a methyl group). This methyl group greatly restricts the possible orientations of triad and substrate as the methyl clashes with either the enzyme backbone or histidine base. [2]
Similar to glutamic acid, Gln contains an amide group where Glu has a carboxyl. Used in proteins and as a storage for ammonia, it is the most abundant amino acid in the body. Arginine: R Arg Functionally similar to lysine. Serine: S Ser Serine and threonine have a short group ended with a hydroxyl group.
Allothreonine is an amino acid with the formula CH 3 CH(OH)CH(NH 2)CO 2 H. It is the diastereomer of the amino acid threonine. Like most other amino acids, allothreonine is a water-soluble colorless solid. Although not one of the proteinogenic amino acids, it has often been the subject for the synthesis of novel proteins using an expanded ...
Threonic acid is a sugar acid derived from threose. The l - isomer is a metabolite of ascorbic acid (vitamin C). [ 1 ] One study suggested that because l -threonate inhibits DKK1 expression in vitro , it may have potential in treatment of androgenic alopecia .
Aside from cleavage, phosphorylation is perhaps the most important chemical modification of proteins. A phosphate group can be attached to the sidechain hydroxyl group of serine, threonine and tyrosine residues, adding a negative charge at that site and producing an unnatural amino acid.
Threonine proteases use the secondary alcohol of their N-terminal threonine as a nucleophile to perform catalysis. [1] [2] The threonine must be N-terminal since the terminal amine of the same residue acts as a general base by polarising an ordered water which deprotonates the alcohol to increase its reactivity as a nucleophile.
Threonine ammonia-lyase (EC 4.3.1.19, systematic name L-threonine ammonia-lyase (2-oxobutanoate-forming), also commonly referred to as threonine deaminase or threonine dehydratase, is an enzyme responsible for catalyzing the conversion of L-threonine into α-ketobutyrate and ammonia: L-threonine = 2-oxobutanoate + NH 3 (overall reaction)