Others require an additional chemical component called a cofactor such as an inorganic ion Fe2+, Mg2+, Zn2+ or a metalloorganic molecule called a coenzyme. (Lehninger 4th Edition)
Enzymes are classified into six classes each with sub classes based on the type of reaction catalyzed. Thus our enzyme of interest Phosphoribosylpyrophosphate (PRPP) Synthetase (Prs) belongs to the class Transferases catalyzing group transfer reactions with its Enzyme Commission Number as 18.104.22.168. (Online Mendelian Inheritance in Man, 2010)
Phosphoribosylpyrophosphate synthetase (Prs) (or Ribose-phosphate diphosphokinase) catalyses the synthesis of phosphoribosyl pyrophosphate (PRPP), an intermediate in nucleotide metabolism for the de novo and salvage pathways of purine and pyrimidine biosynthesis and the biosynthesis of the amino acids histidine and tryptophan.
One of the important specialized pathways of a number of amino acids is the synthesis of purine and pyrimidine nucleotides. The two ringed purine members Adenine, Guanine, Hypoxanthine and Xanthine and the single ringed pyrimidines namely Cytosine, Thymine, Uracil are important for a number of reasons. Most of them, not just ATP, are the sources of energy that drive most of our reactions. ATP is the most commonly used source but GTP is used in protein synthesis as well as a few other reactions. ...