C O M M U N I C A T I O N S
SI). The IPP and DMAPP produced were also isolated and character-
ized (see the SI).16
Supporting Information Available: Complete author lists for refs
15, 17, 27, and 44, purification of 57Fe-labeled IspH protein, Mo¨ssbauer
spectrum of IspH in the presence of NADPH-Fpr-FldA, syntheses of redox
dyes, steady-state kinetic IspH analysis using DT and MV or MDQ, IspH
activities under different conditions, and IspH reaction product character-
ization. This material is available free of charge via the Internet at http://
pubs.acs.org.
From experiments using IspH from various sources along with
iron-sulfur clusters assembled by either in vitro iron-sulfur recon-
stitution or in vivo isc operon-mediated maturation, a wide range of
activities (2.0 nmol min-1 mg-1 to 10.3 µmol min-1 mg-1) have been
reported in the literature in the past decade (Table 3). The reduction
systems used include NAD(P)H-FldA-Fpr, NADPH-ferredoxin
(Fdx)-ferredoxin reductase (Fdr), photoreduced deazaflavin (DAF),
and DT alone or with MV as the electron shuttle. In the literature, the
highest reported activity was for IspH from the malaria parasite
Plasmodium falciparum with ferredoxin (Fd) and ferredoxin-NADP+
reductase (FNR) from the same organism as the reduction system and
NADPH as the electron source.44 For E. coli IspH, Gra¨wert et al.17
reported an activity of 0.7 µmol min-1 mg-1 at 37 °C using NADPH-
Fpr-FldA as the reduction system. Using photoreduced deazaflavin
as the reductant, they reported an activity of 3.4 µmol min-1 mg-1.
However, they could not detect enzymatic activity using DT as the
reducing agent.
References
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Acknowledgment. P.L. was supported by the Boston University
Startup Fund and an NSF CAREER Award (CHE-0748504). We also
thank the NSF-REU program (CHE-0649114) for support of L.C.
(summer 2008).
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