Kinetic and isotopic characterization of l -proline dehydrogenase from mycobacterium tuberculosis

Hector Serrano, John S. Blanchard

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

The monofunctional proline dehydrogenase (ProDH) from Mycobacterium tuberculosis performs the flavin-dependent oxidation of l-proline to Δ1-pyrroline-5-carboxylate in the proline catabolic pathway. The ProDH gene, prub, was cloned into the pYUB1062 vector, and the C-terminal His-tagged 37 kDa protein was expressed and purified by nickel affinity chromatography. A steady-state kinetic analysis revealed a ping-pong mechanism with an overall kcat of 33 ± 2 s-1 and K m values of 5.7 ± 0.8 mM and 3.4 ± 0.3 μM for l-proline and 2,6-dichlorophenolindophenol (DCPIP), respectively. The pH dependence of kcat revealed that one enzyme group exhibiting a pK value of 6.8 must be deprotonated for optimal catalytic activity. Site-directed mutagenesis suggests that this group is Lys110. The primary kinetic isotope effects on V/KPro and V of 5.5 and 1.1, respectively, suggest that the transfer of hydride from l-proline to FAD is rate-limiting for the reductive half-reaction, but that FAD reoxidation is the rate-limiting step in the overall reaction. Solvent and multiple kinetic isotope effects suggest that l-proline oxidation occurs in a stepwise rather than concerted mechanism. Pre-steady-state kinetics reveal an overall kred of 88.5 ± 0.7 s-1, and this rate is subject to a primary kinetic isotope effect of 5.2. These data confirm that the overall reaction is limited by reduced flavin reoxidation in the second half-reaction.

Original languageEnglish (US)
Pages (from-to)5009-5015
Number of pages7
JournalBiochemistry
Volume52
Issue number29
DOIs
StatePublished - Jul 23 2013

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Proline Oxidase
Mycobacterium tuberculosis
Proline
Kinetics
Isotopes
Flavin-Adenine Dinucleotide
2,6-Dichloroindophenol
Affinity chromatography
Oxidation
Mutagenesis
Site-Directed Mutagenesis
Nickel
Affinity Chromatography
Hydrides
Catalyst activity
Genes
Enzymes
Proteins

ASJC Scopus subject areas

  • Biochemistry

Cite this

Kinetic and isotopic characterization of l -proline dehydrogenase from mycobacterium tuberculosis. / Serrano, Hector; Blanchard, John S.

In: Biochemistry, Vol. 52, No. 29, 23.07.2013, p. 5009-5015.

Research output: Contribution to journalArticle

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