Literature summary for 1.13.12.16 extracted from

Francis, K.; Gadda, G.
Inflated kinetic isotope effects in the branched mechanism of Neurospora crassa 2-nitropropane dioxygenase (2009), Biochemistry, 48, 2403-2410.

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Organism

Organism	UniProt	Comment	Textmining
Neurospora crassa	-	-	-

Substrates and Products (Substrate)

Substrates	Comment Substrates	Organism	Products	Comment (Products)	Rev.	Reac.
nitroethane + O2	The kinetic isotope effect on the second-order rate constant for nitronate formation, kcat/Km, decreases from an upper limiting value of 23 at low pH to a lower limiting value of 11 at high pH. The difference in the kinetic isotope effects arises from the branching of an enzyme-ethylnitronate reaction intermediate through oxidative and nonoxidative turnover. This branching is isotope sensitive due to a kinetic isotope effect on nitronate release rather than on flavin reduction. The kinetic isotope effect on ethylnitronate release arises from the deprotonation of histidine 196, which provides electrostatic interactions with the nitronate to keep it bound in the active site for oxidation. The isotope effect on branching results in an inflation of the kinetic isotope observed for the nonoxidative pathway to values that are larger than the intrinsic values associated with C-H bond cleavage	Neurospora crassa	acetaldehyde + HNO2	-	?

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Release 2023.1 (January 2023)