Phosphorylation of hydroxyl groups

Protein kinases comprise a series of closely related enzymes that catalyze the phosphorylation of hydroxyl groups in enzymes, which regulate a wide range of physiological processes. Phosphorylation may either turn the function of the target on or off. Inhibitors of the protein C kinases (PKC) that are involved in cell proliferation have attracted particular... 

Acetylation of hydroxyl groups and esterification of carboxyl groups have been observed ia a limited number of cases but, ia geaeral, have ao preparative advantage over chemical methods. By comparison, phosphorylation has been useful ia the preparatioa of modified purine and pyrimidine mononucleotides from their corresponding nucleosides, eg, 6-thioguanosiae [85-31-4] (51) (97). 

ATP + (d)CMP = ADP + (d)CDP (<4> formation of a ternary complex, addition of substrates is random [5] <1> reaction proceeds by a sequential mechanism, a ternary complex of the enzyme with both substrates is formed as the central intermediate in the reaction [12] <3> reaction mechanism is sequential and nonequilibrium in nature, substrates bind to the enzyme in a random order, substrate binding is cooperative [14] <7> the mechanism is analogous to the phosphoryl transfer mechanism in cAMP-dependent protein kinase that phosphorylates the hydroxyl groups of serine residues [16] <8> random bi-bi mechanism [17])... 

Covalent modification by phosphorylation and dephosphorylation of hydroxyl groups on amino acid side chains. 

Just as there are two classes of protein kinases, there are also two main classes of protein phosphatases (PPs), the enzymes catalysing the hydrolysis of phosphate from a peptide structure. According to whether the phosphorylated aminoacid hydroxyl group is aliphatic or aromatic, serine/threonine PPs and tyrosine PPs are recognised. 

In keeping with its biogenetic origin m three molecules of acetic acid mevalonic acid has six carbon atoms The conversion of mevalonate to isopentenyl pyrophosphate involves loss of the extra carbon as carbon dioxide First the alcohol hydroxyl groups of mevalonate are converted to phosphate ester functions—they are enzymatically phosphorylated with introduction of a simple phosphate at the tertiary site and a pyrophosphate at the primary site Decarboxylation m concert with loss of the terti ary phosphate introduces a carbon-carbon double bond and gives isopentenyl pyrophos phate the fundamental building block for formation of isoprenoid natural products... 

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