Biochemistry Nucleotides 6c58ac8e Deficiency of which of the following enzyme leads to toxicity of 5-fluorouracil? A Purine nucleoside phosphorylase B Dihydropyrimidine dehydrogenase C PRPP synthase D Adenosine deaminase High-Yield Explanation 5-fluorouracil is acted upon by dihydropyrimidine dehydrogenase - Deficiency - accumulation of 5-FU - toxicity.