Enzymatic ribonucleotide reduction is accomplished via a free radical mechanism. Which of the following statements is true regarding this process?
A) The substrate specificity site on the R1 homodimer determines if the enzyme is active or inactive.
B) R2 has a single active site containing two Fe atoms that generate the free radicals required for reduction.
C) R2, but not R1, function in the delivery of reducing equivalents.
D) R2 homodimer carries two regulatory sites.
E) A final decarboxylation forms the deoxyribonucleotide product.

Question

Quizplus · Accepted Answer

R2 has a single active site containing two Fe atoms that generate the free radicals required for reduction. The substrate specificity site on the R1 homodimer does not determine if the enzyme is active or inactive, but rather determines the specificity for the substrate. R1 and R2 both participate in the delivery of reducing equivalents. R2 homodimer carries only one regulatory site. The final step of ribonucleotide reduction involves the addition of an H+ instead of a decarboxylation.

Enzymatic Ribonucleotide Reduction Is Accomplished Via a Free Radical Mechanism