Amino-, metal catalysts, action

Benzol/] quinolines formation of, 150, 162 metal catalysts, action on, 189, 196 Benzol/i]quinoline, metal catalysts, action on, 189, 196 Benzoselenazole, 2-amino-, 68 Benzoselenazole-2-thione, 62 Benzoselenazol-2-one, 49 Benzo-1,2,4-thiadiazin-3-ones, methyla -tion of, 259 Benzothiazoles 2-acylamino-, 77... 

Frequently enzymes act in concert with small molecules, coenzymes or cofactors, which are essential to the function of the amino acid side chains of the enzyme. Coenzymes or cofactors are distinguished from substrates by the fact that they function as catalysts. They are also distinguishable from inhibitors or activators in that they participate directly in the catalyzed reaction. Chapter 10, Vitamins and Coenzymes, starts with a description of the relationship of water-soluble vitamins to their coenzymes. Next, the functions and mechanisms of action of coenzymes are explained. In the concluding sections of this chapter, the roles of metal cofactors and lipid-soluble vitamins in enzymatic catalysis are briefly discussed. 

The role of pyridoxal in the transamination reaction has been extensively investigated by comparing the mechanism of action of nonenzymic transamination (see Fig. 4-28) in the presence of metal (iron) acting as a catalyst to the transamination catalyzed by the specific proteins. The mechanism of the nonenzymic transamination was deduced from a series of rather simple observations (1) when an amino acid is added to a dilute solution of pyridoxal or pyridoxine phosphate, the absorption maximum of the solution shifts from 345 mp to 430 mp. This change in absorption... 

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