General Principles of Screening for Histone-Modifying Enzymes

General Principles of Screening for Histone-Modifying Enzymes 

Enzymes that cleave off modifications may be assayed by measuring the formation of either the protein or a protein-mimicking substrate or the small molecule produd or byproducts (like acetate for histone deacetylases, or formaldehyde or hydrogen peroxide for histone demethylases). Transferases may generally be screened by measuring the conversion of the cosubstrate or quantitatin the formation of the 

The equilibrium of reversible histone lysine acetylation is maintained by histone deacetylases (H D ACs) on one hand and histone acetyltransferases on the other hand. Human histone deacetylases can be separated into four classes [15]. HDACs of class I, II and IV are zinc-dependent amidohydrolases, whereas class III HDACs, also referred to as sirtuins, have a mechanism that is dependent on NAD [16]. As histone deacetylases have been widely studied, it is not surprising that there are also a large number of assays existing that have helped to characterize modulators of these enzymes and subsequently the enzymes themselves. 

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