Noun
English Wikipedia has an article on:phosphoribosylaminoimidazole synthetaseWikipedia
phosphoribosylaminoimidazole synthetase (uncountable)
(biochemistry) An enzyme involved in nucleotide synthesis, catalyzing the conversion of 5'-phosphoribosyl-5-aminoimidazole into 5-phosphoribosyl-4-carboxy-5-aminoimidazole.