2009
DOI: 10.1021/bi900499w
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Use of pH and Kinetic Isotope Effects To Establish Chemistry as Rate-Limiting in Oxidation of a Peptide Substrate by LSD1

Abstract: The mechanism of oxidation of a peptide substrate by the flavoprotein lysine-specific demethylase (LSD1) has been examined using the effects of pH and isotopic substitution on steady-state and rapid-reaction kinetic parameters. The substrate contained the N-terminal 21 residues of histone H3, with a dimethylated lysyl residue at position 4. At pH 7.5, the rate constant for flavin reduction, kred, equals kcat, establishing the reductive half reaction as rate-limiting at physiological pH. Deuteration of the lysy… Show more

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Cited by 35 publications
(65 citation statements)
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“…However, there is no evidence for an intermediate in the PAO-catalyzed oxidation of any amine, including those studied here (20, 26). It should be noted that similar small isotope effects have been seen with the flavoprotein amine oxidases LSD1 (38) and tryptophan monooxygenase (21), both of which are in the MAO structural family, and with D-amino acid oxidase (39), which has a different structure. Thus, the combination of steady-state and rapid-reaction kinetics is most consistent with CH bond cleavage being the rate-limiting step in the oxidation of N, N'-dibenzyl-1,4-diaminobutanes by PAO.…”
Section: Discussionmentioning
confidence: 64%
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“…However, there is no evidence for an intermediate in the PAO-catalyzed oxidation of any amine, including those studied here (20, 26). It should be noted that similar small isotope effects have been seen with the flavoprotein amine oxidases LSD1 (38) and tryptophan monooxygenase (21), both of which are in the MAO structural family, and with D-amino acid oxidase (39), which has a different structure. Thus, the combination of steady-state and rapid-reaction kinetics is most consistent with CH bond cleavage being the rate-limiting step in the oxidation of N, N'-dibenzyl-1,4-diaminobutanes by PAO.…”
Section: Discussionmentioning
confidence: 64%
“…The polar nucleophilic mechanism proposed by Edmondson (45) involves concerted formation of a 4a-alkylated isoalloxazine ring and proton abstraction of the substrate α-hydrogen. Direct transfer of a hydride from the α-C of the substrate to the N5 position of the flavin is the consensus mechanism for the D-amino acid oxidase structural family of flavin amine oxidases (16, 46); its applicability to the MAO structural family is supported by kinetic isotope effects and the failure to detect intermediates in the reactions of these enzymes (1720, 38, 45). The ρ value of −0.59 for PAO at pH 8.6 reported here is most consistent with a direct hydride transfer reaction in which there is little charge development in the transition state for carbon-hydrogen bond cleavage.…”
Section: Discussionmentioning
confidence: 99%
“…We should note that our derived kinetic values are in reasonable agreement with previously reported values with and without CoREST. 13,22,23,30 …”
Section: Resultsmentioning
confidence: 99%
“…30,38 The unmodified 21-mer histone H3 product peptide (H3 1–21 ) was synthesized and purified in a similar fashion. A C-terminal GYG was added to both the substrate and product peptides to allow for quantification of the peptide concentration at 280 nm, using an extinction coefficient of 1490 M −1 cm −1 for tyrosine.…”
Section: Methodsmentioning
confidence: 99%
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