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GENERAL BIOCHEMISTRY 



drolytic enzymes and for two oxidation catalysts still called the yellow 

 enzymes. The roots of names for enzymes are usually taken from the 

 substrate of major interest and often consist of two (sometimes three) 

 words, one designating the substrate, the other specifying the change 

 produced in the substrate. For example, a-amylase catalyzes the hy- 

 drolysis of the a-amylose component of starch, and alcohol dehy- 

 drogenase catalyzes a particular dehydrogenation of ethanol. There 

 are a few special cases not named from the substrate but having the 

 typical ending. Invertase promotes the conversion of sucrose to a mix- 

 ture of D-glucose and D-fructose. The name refers to both the inversion 

 of optical rotation that takes place and to the products in this mixture 

 called invert sugar. 



TABLE 6-1. Classification of Enzymes 



Enzymes Substrates or Reactions 



Hydrolytic enzymes 



Proteases (proteolytic enzymes) 



Esterases and lipases 



Carbohydrases (glycosidases) 



Phosphatases 



Amidases 



Peptidases 



Oxidation-reduction enzymes 

 Oxidases 



Dehydrogenases 



Transferring enzymes 

 Transphosphorylases 

 Transglycosidases 

 Transpeptidases 

 Transaminases 

 Transmethylases 

 Transacylases 



Addition enzymes 

 Isomerizing enzymes 



Carboxylation enzymes 



Decarboxylases, carboxylases 



Hydrolysis 



Proteins, peptides 



Esters, lipides 



Glycosides (acetals) 



Phosphate esters and anhydrides 



Amides 



Small peptides 



Oxidation and reduction 



Oxidations with O2 or H2O2, decomposi- 

 tion of H2O2 

 Transfer of hydrogen atoms to or from 

 substrates 



Exchange of groups between substrates 

 Phosphate 

 Carbohydrate 

 Amide, amino acid 

 Amino 

 Methyl 

 Ac>I 



Addition of HoO or NH3 to carbon-carbon 

 double bonds 



Change of configuration about a carbon 

 atom or other rearrangements in a sub- 

 strate molecule 



Elimination or addition of CO2 



