A secondary kinetic isotope effect study of the 1-deoxy-D-xylulose-5- phosphate reductoisomerase-catalyzed reaction

Evidence for a retroaldol-aldol rearrangement

Jeffrey W. Munos, Xiaotao Pu, Steven O. Mansoorabadi, Hak Joong Kim, Hung Wen Liu

Research output: Contribution to journalArticle

51 Citations (Scopus)

Abstract

1-Deoxy-D-xylulose 5-phosphate (DXP) reductoisomerase (DXR, also known as methyl-D-erythritol 4-phosphate (MEP) synthase) is a NADPH-dependent enzyme, which catalyzes the conversion of DXP to MEP in the nonmevalonate pathway of isoprene biosynthesis. Two mechanisms have been proposed for the DXR-catalyzed reaction. In the ,-ketol rearrangement mechanism, the reaction begins with deprotonation of the C-3 hydroxyl group followed by a 1,2-migration to give methylerythrose phosphate, which is then reduced to MEP by NADPH. In the retroaldol/aldol rearrangement mechanism, DXR first cleaves the C3-C4 bond of DXP in a retroaldol manner to generate a three-carbon and a two-carbon phosphate bimolecular intermediate. These two species are then reunited by an aldol reaction to form a new C-C bond, yielding an aldehyde intermediate. Subsequent reduction by NADPH affords MEP. To differentiate these mechanisms, we have prepared [3-2H]- and [4-2H]-DXP and carried out a competitive secondary kinetic isotope effect (KIE) study of the DXR reaction. The normal 2° KIEs observed for [3-2H]- and [4-2H]-DXP provide compelling evidence supporting a retroaldol/aldol mechanism for the rearrangement catalyzed by DXR, with the rate-limiting step being cleavage of the C3-C4 bond of DXP.

Original languageEnglish
Pages (from-to)2048-2049
Number of pages2
JournalJournal of the American Chemical Society
Volume131
Issue number6
DOIs
Publication statusPublished - 2009 Feb 18
Externally publishedYes

Fingerprint

Isotopes
Phosphates
Kinetics
NADP
Carbon
Deprotonation
Biosynthesis
Aldehydes
Hydroxyl Radical
1-deoxy-D-xylulose 5-phosphate reductoisomerase
1-deoxylulose 5-phosphate
3-hydroxybutanal
erythritol 4-phosphate
2-C-methylerythritol 4-phosphate
Enzymes
Isoprene

ASJC Scopus subject areas

  • Chemistry(all)
  • Catalysis
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

A secondary kinetic isotope effect study of the 1-deoxy-D-xylulose-5- phosphate reductoisomerase-catalyzed reaction : Evidence for a retroaldol-aldol rearrangement. / Munos, Jeffrey W.; Pu, Xiaotao; Mansoorabadi, Steven O.; Kim, Hak Joong; Liu, Hung Wen.

In: Journal of the American Chemical Society, Vol. 131, No. 6, 18.02.2009, p. 2048-2049.

Research output: Contribution to journalArticle

@article{548675fb9b4a4b8aa778bcbdb709dfb8,
title = "A secondary kinetic isotope effect study of the 1-deoxy-D-xylulose-5- phosphate reductoisomerase-catalyzed reaction: Evidence for a retroaldol-aldol rearrangement",
abstract = "1-Deoxy-D-xylulose 5-phosphate (DXP) reductoisomerase (DXR, also known as methyl-D-erythritol 4-phosphate (MEP) synthase) is a NADPH-dependent enzyme, which catalyzes the conversion of DXP to MEP in the nonmevalonate pathway of isoprene biosynthesis. Two mechanisms have been proposed for the DXR-catalyzed reaction. In the ,-ketol rearrangement mechanism, the reaction begins with deprotonation of the C-3 hydroxyl group followed by a 1,2-migration to give methylerythrose phosphate, which is then reduced to MEP by NADPH. In the retroaldol/aldol rearrangement mechanism, DXR first cleaves the C3-C4 bond of DXP in a retroaldol manner to generate a three-carbon and a two-carbon phosphate bimolecular intermediate. These two species are then reunited by an aldol reaction to form a new C-C bond, yielding an aldehyde intermediate. Subsequent reduction by NADPH affords MEP. To differentiate these mechanisms, we have prepared [3-2H]- and [4-2H]-DXP and carried out a competitive secondary kinetic isotope effect (KIE) study of the DXR reaction. The normal 2° KIEs observed for [3-2H]- and [4-2H]-DXP provide compelling evidence supporting a retroaldol/aldol mechanism for the rearrangement catalyzed by DXR, with the rate-limiting step being cleavage of the C3-C4 bond of DXP.",
author = "Munos, {Jeffrey W.} and Xiaotao Pu and Mansoorabadi, {Steven O.} and Kim, {Hak Joong} and Liu, {Hung Wen}",
year = "2009",
month = "2",
day = "18",
doi = "10.1021/ja807987h",
language = "English",
volume = "131",
pages = "2048--2049",
journal = "Journal of the American Chemical Society",
issn = "0002-7863",
publisher = "American Chemical Society",
number = "6",

}

TY - JOUR

T1 - A secondary kinetic isotope effect study of the 1-deoxy-D-xylulose-5- phosphate reductoisomerase-catalyzed reaction

T2 - Evidence for a retroaldol-aldol rearrangement

AU - Munos, Jeffrey W.

AU - Pu, Xiaotao

AU - Mansoorabadi, Steven O.

AU - Kim, Hak Joong

AU - Liu, Hung Wen

PY - 2009/2/18

Y1 - 2009/2/18

N2 - 1-Deoxy-D-xylulose 5-phosphate (DXP) reductoisomerase (DXR, also known as methyl-D-erythritol 4-phosphate (MEP) synthase) is a NADPH-dependent enzyme, which catalyzes the conversion of DXP to MEP in the nonmevalonate pathway of isoprene biosynthesis. Two mechanisms have been proposed for the DXR-catalyzed reaction. In the ,-ketol rearrangement mechanism, the reaction begins with deprotonation of the C-3 hydroxyl group followed by a 1,2-migration to give methylerythrose phosphate, which is then reduced to MEP by NADPH. In the retroaldol/aldol rearrangement mechanism, DXR first cleaves the C3-C4 bond of DXP in a retroaldol manner to generate a three-carbon and a two-carbon phosphate bimolecular intermediate. These two species are then reunited by an aldol reaction to form a new C-C bond, yielding an aldehyde intermediate. Subsequent reduction by NADPH affords MEP. To differentiate these mechanisms, we have prepared [3-2H]- and [4-2H]-DXP and carried out a competitive secondary kinetic isotope effect (KIE) study of the DXR reaction. The normal 2° KIEs observed for [3-2H]- and [4-2H]-DXP provide compelling evidence supporting a retroaldol/aldol mechanism for the rearrangement catalyzed by DXR, with the rate-limiting step being cleavage of the C3-C4 bond of DXP.

AB - 1-Deoxy-D-xylulose 5-phosphate (DXP) reductoisomerase (DXR, also known as methyl-D-erythritol 4-phosphate (MEP) synthase) is a NADPH-dependent enzyme, which catalyzes the conversion of DXP to MEP in the nonmevalonate pathway of isoprene biosynthesis. Two mechanisms have been proposed for the DXR-catalyzed reaction. In the ,-ketol rearrangement mechanism, the reaction begins with deprotonation of the C-3 hydroxyl group followed by a 1,2-migration to give methylerythrose phosphate, which is then reduced to MEP by NADPH. In the retroaldol/aldol rearrangement mechanism, DXR first cleaves the C3-C4 bond of DXP in a retroaldol manner to generate a three-carbon and a two-carbon phosphate bimolecular intermediate. These two species are then reunited by an aldol reaction to form a new C-C bond, yielding an aldehyde intermediate. Subsequent reduction by NADPH affords MEP. To differentiate these mechanisms, we have prepared [3-2H]- and [4-2H]-DXP and carried out a competitive secondary kinetic isotope effect (KIE) study of the DXR reaction. The normal 2° KIEs observed for [3-2H]- and [4-2H]-DXP provide compelling evidence supporting a retroaldol/aldol mechanism for the rearrangement catalyzed by DXR, with the rate-limiting step being cleavage of the C3-C4 bond of DXP.

UR - http://www.scopus.com/inward/record.url?scp=67849094631&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=67849094631&partnerID=8YFLogxK

U2 - 10.1021/ja807987h

DO - 10.1021/ja807987h

M3 - Article

VL - 131

SP - 2048

EP - 2049

JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

SN - 0002-7863

IS - 6

ER -