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Characterization of Sulfoxygenation and Structural Implications of Human Flavin-Containing Monooxygenase Isoform 2 (FMO2.1) Variants S195L and N413K
- Source :
- Drug Metabolism and Disposition. 37:1785-1791
- Publication Year :
- 2009
- Publisher :
- American Society for Pharmacology & Experimental Therapeutics (ASPET), 2009.
-
Abstract
- Catalytically active human flavin-containing monooxygenase isoform 2 (FMO2.1) is encoded by an allele detected only in individuals of African or Hispanic origin. Genotyping and haplotyping studies indicate that S195L and N413K occasionally occur secondary to the functional FMO2*1 allele encoding reference protein Gln472. Sulfoxygenation under a range of conditions reveals the role these alterations may play in individuals expressing active FMO2 and provides insight into FMO structure. Expressed S195L lost rather than gained activity as pH was increased or when cholate was present. The activity of S195L was mostly eliminated after heating at 45°C for 5 min in the absence of NADPH, but activity was preserved if NADPH was present. By contrast, Gln472 was less sensitive to heat, a response not affected by NADPH. A major consequence of the S195L mutation was a mean 12-fold increase in Km for NADPH compared with Gln472. Modeling an S213L substitution, the equivalent site, in the structural model of FMO from the Methylophaga bacterium leads to disruption of interactions with NADP+. N413K had the same pattern of activity as Gln472 in response to pH, cholate, and magnesium, but product formation was always elevated by comparison. N413K also lost more activity when heated than Gln472; however, NADPH attenuated this loss. The major effects of N413K were increases in velocity and kcat compared with Gln472. Although these allelic variants are expected to occur infrequently as mutations to the FMO2*1 allele, they contribute to our overall understanding of mammalian FMO structure and function.
- Subjects :
- Models, Molecular
Gene isoform
Protein Denaturation
Hot Temperature
Genotype
Protein Conformation
Pharmaceutical Science
Flavin-containing monooxygenase
medicine.disease_cause
Polymorphism, Single Nucleotide
Isozyme
Structure-Activity Relationship
Methylophaga
Protein structure
Enzyme Stability
medicine
Humans
Magnesium
Allele
Databases, Protein
Pharmacology
Mutation
biology
Articles
Hydrogen-Ion Concentration
Monooxygenase
biology.organism_classification
Recombinant Proteins
Isoenzymes
Kinetics
Phenotype
Biochemistry
Sulfoxides
Oxygenases
Cholates
Oxidation-Reduction
NADP
Subjects
Details
- ISSN :
- 1521009X and 00909556
- Volume :
- 37
- Database :
- OpenAIRE
- Journal :
- Drug Metabolism and Disposition
- Accession number :
- edsair.doi.dedup.....3761d589a64ff809ceb1dc190f4b0329