13. Adenylosuccinase (adenylosuccinate lyase) catalyzes the reaction to remove ______ after ______ has formed an amide with a carbonyl group in purine biosynthesis.
(A) succinate; glutamate
(B) succinate; aspartate
(C) fumarate; alanine
(D) fumarate; aspartate
(E) alpha-ketoglutarate; glutamate