Serine/threonine/tyrosine

Kosako, H Gotoh, Y Matsuda, S Ishikawa, M and Nishida, E. (1992). Xenopus MAP kinase activator is a serine/threonine/tyrosine kinase activated by threonine phosphorylation. EMBO J. 11 2903-2908. 

By means of a procedure described above, Hanson and Fittkau (HI) isolated seventeen different peptides from normal urine. One of them, not belonging to the main peptide fraction, consisted of glutamic acid, and phenylalanine with alanine as the third not definitely established component. The remaining peptides contained five to ten different amino acid residues and some unidentified ninhydrin-positive constituents. Four amino acids, i.e., glutamic acid, aspartic acid, glycine, and alanine, were found in the majority of the peptides analyzed. Twelve peptides contained lysine and eight valine. Less frequently encountered were serine, threonine, tyrosine, leucine, phenylalanine, proline, hydroxyproline, and a-aminobutyric acid (found only in two cases). The amino acid composi-... 

It should be appreciated that amino acids such as serine, threonine, tyrosine, and cysteine all contain side-chain alcohol or thiol groups that may participate in hydrogen bonding and stabilize a particular protein conformation. 

The CBS prediction server also provides services for predicting O-glycosylation sites (NetGly) in mammalian proteins (http //www.cbs.dtu.dk/services/NetQGly-2.0/) and phosphorylation sites (NetPhos) in eukaryotic proteins (http //www.cbs.dtu.dk/ services/NetPhos/). Paste the query sequence and click the Submit Sequence button to receive the predicted results. NetOGly returns tables of potential versus threshold assignments for threonine and serine residues as well as a plot of O-glycosylation potential versus sequence position. NetPhos returns tables of context (nanopeptides, [S,T,Y] + 4 residues) and scores for serine/threonine/tyrosine predictions. 

The individual amino acids of a protein can be liberated by hydrolyzing the peptide (amide) bonds (-CO-NH-) that link them. The usual procedure is to dissolve the peptide or protein in 6 N HC1 and heat the solution in a sealed, evacuated tube at 100°C for 8 to 72 hr (or for shorter times at higher temperatures). All amide linkages (including the side chain amides of glutamine and asparagine) are cleaved under these conditions. Certain amino acids are entirely (tryptophan) or partially (serine, threonine, tyrosine, cysteine) destroyed, so that special precautions are required for the quantitative determination of these amino acids. 

Serine Threonine Tyrosine Cysteine Asparagine Glutamine... 

One of the most widespread modifications is phosphorylation or dephosphorylation of various amino acid side chains (e.g., serine, threonine, tyrosine, and histidine). These kinds of modification are most often a part of complex regulatory pathways, frequently under hormonal control. (See kinase cascade). 

Another group of amino acids has polar side chains that are electrically neutral (uncharged) at neutral pH. This group includes serine, threonine, tyrosine. 

Other alkylating agents that react with cysteine residue side-chains are methyl iodide, Wethylmaleimide, and acrylonitrile. Alkylating agents react most rapidly with cysteine residues but more slowly with lysine, histidine, methionine, serine, threonine, tyrosine, aspartic acid, and glutamic acid residue side-chains. 

Amino acids with hydroxyl groups in the side chain Serine Threonine Tyrosine -CH2-OH -CH(CH2)-0H -CH2-C6H4-OH... 

Hydroxyl Serine, threonine, tyrosine Hydrogen bonding, acid-base catalysis... 

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