162 UNITY AND DIVERSITY IN BIOCHEMISTRY 



(h) CoA Transferases 



These catalyse the transfer of CoA from an acyl-CoA to a series of fatty 

 acids e.g. the microbial CoA transferase catalyses the reaction : 



acetyl-CoA + propionate ^ propionyl-CoA + acetate 



or the CoA transferase from animals catalyses the reaction : 



succinyl-CoA + acetoacetate ^ acetoacetyl-CoA + succinate 



(/) Other Transferases 



Other groups of transferases, which have been little studied up to the 

 present, are the trans-sulphurases, transglutamases, transaspartases, etc. 



D. OXIDO-REDUCTION EnZYMES 

 (OXIDOREDUCTASES, ElECTRONTRANSFERASES) 



These are transferases of a particular type, transferring electrons 

 accompanied by protons (transhydrogenases) or electrons alone (trans- 

 electronases) from a donor to an acceptor. If the acceptor is oxygen the 

 transhydrogenase or transelectronase is called aerobic. If the acceptor is 

 another type of molecule, they are called anaerobic. Here are some examples 

 of these four types : 



(a) Anaerobic transhydrogenases 



H H 



/ / 



R + R' ^ R + R' 



\ \ 



H H 



e.g. DPNH -^ pyruvate transhydrogenase (lactic dehydrogenase) 



DPNH -^ aldehyde transhydrogenase (alcohol dehydrogenases). 



{h) Aerobic transhydrogenase 



H 



/ 

 R + O2 ^ R + H2O2 



\ 

 H 



e.g. j8-glucose -» Oa-transhydrogenase or glucose-oxidase 



Xanthine -> Og-transhydrogenase or xanthine-oxidase. 



