| Abstract
| - Lumazine synthase and riboflavin synthase catalyze the last two steps in the biosynthesis ofriboflavin, a vitamin that is involved in many critical biochemical reactions that are essential forthe maintenance of life. To obtain inhibitors and structural probes that could be useful in studyingthe structures of bound reaction intermediates, the ribitylamino N−H moiety of the lumazinesynthase substrate was replaced by CH2 and N−CH3 groups. The CH2 replacement unexpectedlyand completely abolished the affinity for lumazine synthase, thus revealing a critical, yetunexplained, role of the ribitylamino N−H moiety in conferring affinity for the enzyme. In contrast,the N−CH3 replacement resulted in an inhibitor of both lumazine synthase and riboflavin synthase.Replacement of the ribitylamino N−H moiety with epimeric C−F moieties led to inhibition oflumazine synthase and riboflavin synthase when combined with the replacement of the 5-aminogroup with a nitro substituent.
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