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A mechanism for substrate-Induced formation of 6-hydroxyflavin mononucleotide catalyzed by C30A trimethylamine

Xingliang Lu1, Dejan Nikolic, Deanna J Mitchell

  • 1Department of Chemistry, Northwestern University, Evanston, IL 60208-3113, USA.

Bioorganic & Medicinal Chemistry Letters
|November 1, 2003
PubMed

Insights

Researchers investigated the source of a hydroxyl group in 6-hydroxyFMN, a product of trimethylamine dehydrogenase. Experiments using isotopically labeled oxygen confirmed the hydroxyl group originates from molecular oxygen, not water.

Area of Science:

  • Biochemistry
  • Enzymology
  • Oxidation Reactions

Background:

  • Trimethylamine dehydrogenase (TMADH) catalyzes the oxidation of trimethylamine.
  • Flavin adenine dinucleotide (FMN) is a crucial cofactor in TMADH activity.
  • Substrate-induced transformation of FMN leads to the formation of 6-hydroxyFMN.

Purpose of the Study:

  • To elucidate the origin of the 6-hydroxyl group in 6-hydroxyFMN produced by the C30A mutant of TMADH.
  • To differentiate between molecular oxygen and water as the source of the hydroxyl oxygen atom.

Main Methods:

  • Utilizing a C30A mutant of trimethylamine dehydrogenase.
  • Conducting the FMN to 6-hydroxyFMN conversion in the presence of H(2)(18)O and 18O(2).
  • Analyzing the isotopic composition of the 6-hydroxyl group in the product.

Main Results:

  • The 6-hydroxyl group of 6-hydroxyFMN is demonstrably derived from molecular oxygen (18O(2)).
  • No incorporation of oxygen from water (H(2)(18)O) into the 6-hydroxyl group was observed.
  • This finding clarifies the oxygen source in the FMN transformation pathway.

Conclusions:

  • The oxygen atom incorporated into the 6-hydroxyl group of 6-hydroxyFMN originates exclusively from molecular oxygen.
  • This study provides critical mechanistic insight into the enzymatic oxidation involving trimethylamine dehydrogenase and FMN.
  • The results highlight the specificity of oxygen incorporation in flavin-dependent oxidation reactions.

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