BIOCHEMISTRY. For the article ”Bioinorganic Chemistry Special Feature: An engineered two-iron superoxide reductase lacking the [Fe(SCys)4] site retains its catalytic properties in vitro and in vivo,” by Joseph P. Emerson, Diane E. Cabelli, and Donald M. Kurtz, Jr., which appeared in issue 7, April 1, 2003, of Proc. Natl. Acad. Sci. USA (100, 3802-3807; First Published March 13, 2003; 10.1073/pnas.0537177100), the authors note that they inadvertently labeled the time axis in Fig. 6 as hours instead of seconds. The corrected figure and its legend appear below. This correction does not affect the conclusions of the article.
Fig. 6.
Dependence of NADPH/superoxide oxidoreductase activity on wild-type, C13S, and N-terminal 2Fe-SORs. Rates of NADPH consumption were monitored at room temperature in a 1-ml cuvette as decreases in absorbance at 340 nm (NADPH ε340 = 6,220 M–1·cm–1) in solutions containing (in the added order) 500 μM xanthine, 100 μM NADPH, 186 units/ml catalase, 1 μM Rub, 1 μM spinach ferredoxin:NADP+ oxidoreductase, and either wild-type or C13S 2Fe-SOR (1 μM in [Fe(NHis)4(SCys)] sites) or N-terminal 2Fe-SOR (1 μMin iron sites). After recording a ”baseline” NADPH consumption rate for 50 sec, a precalibrated amount of xanthine oxidase was added to produce a flux of 12μM superoxide per min, and NADPH consumption was monitored for several minutes. Absorbance spikes caused by the various additions and mixing are omitted, and the traces obtained with each SOR are offset vertically by an arbitrary amount for clarity.