Acetylase

Acetylcholine is the product of the reaction between choline and acetyl coenzyme A in the presence of choline acetylase (41). 

Biochemical functions of each gene. I-V = transferase l-V. Acy - acetylases I II. Ket = ketaiase. Pol = polymerase. Exp - export... 

Examples of such systems include the reactions of kinases, phosphatases, hydroxylases, acetylases, ubiquitin transferases, and many other enzyme classes that represent attractive targets for drug discovery. There are several mechanisms by which an enzyme can catalyze these types of reactions, and the details of the mechanism are important in determining the best approach to designing activity assays for the enzyme and for proper evaluation of inhibitors that are identified through those activity assays. 

Co regulators of transcription — histone acetylases modulate chromatin structure 461... 

The PDHC catalyzes the irreversible conversion of pyruvate to acetyl-CoA (Fig. 42-3) and is dependent on thiamine and lipoic acid as cofactors (see Ch. 35). The complex has five enzymes three subserving a catalytic function and two subserving a regulatory role. The catalytic components include PDH, El dihydrolipoyl trans-acetylase, E2 and dihydrolipoyl dehydrogenase, E3. The two regulatory enzymes include PDH-specific kinase and phospho-PDH-specific phosphatase. The multienzyme complex contains nine protein subunits, including... 

Consequence prolonged respiratory paralysis on exposure to the drug Suxamethonium (succinylcholine) for muscle relaxation for anesthesia Slow acetylator phenotype, due to mutations in liver N-acetylase transferase,... 

Gayther SA, Batley SJ, Linger L, Bannister A, Thorpe K, Chin SF, Daigo Y, Russell P, Wilson A, Sowter HM, Delhanty JD, Ponder BA, Kouzarides T, Caldas C (2000) Mutations truncating the EP300 acetylase in human cancers. Nat Genet 24 300-303... 

Involvement of the TIP60 histone acetylase complex in DNA repair and apoptosis. Cell 102 463-473... 

Histone acetylases (fevor gene expression) and deacefylases (favor inactive chromatin)... 

Recruit chromatin-modifying proteins such as histone acetylases or deacetylases... 

In summary what have we learned in 25 years In some areas, surprisingly little— for example, we cannot say that we really understand the condensed chromatin fiber structure much better than we did in 1978. Although the significance of the great majority of histone variants remains unknown, replacement histones appear now to be involved in major chromosomal functions. There are areas in which we have accrued incredible amounts of detailed information yet still do not quite know what to do with it. Histone acetylation is a prime example. Allfrey et al. [56] could predict its role in a general sense in 1964. We now know a whole rogue s gallery of acetylases and deacetylases plus the specific histone sites for many. Nevertheless, authorities in the field must still write in 2000, The mechanisms by which histone acetylation affects chromatin structure and transcription is not yet clear [58]. 

In the resting state, the lysine residues in the N-terminal tail of the histones (see p. 238) are not acetylated. In this state, which can be produced by histone deacetylases [1], the nucleosomes are stable. It is only the interaction of activator and regulator proteins with their control elements that allows the binding of coactivator complexes that have histone acetylase activity [2]. They acetylate the histone tails and thereby loosen the nu-cleosome structure suf ciently for the basal transcription complex to form. 

Kouzarides, T. (1999) Histone acetylases and deacetylases in cell proliferation. Current Opinion in Genetics d. Development, 9, 40-48. 

This enzyme [EC 2.3.1.87], also known as serotonin acetyltransferase and serotonin acetylase, catalyzes the reaction of acetyl-CoA and arylalkylamine to generate coenzyme A and A-acetylarylalkylamine. The enzyme exhibits a rather narrow specificity toward other aryl-alkylamines. This enzyme is distinct from arylamine acetyltransferase. 

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