NS-N1-MD enhances the rate and extent of heme transfer from metHb to N2.

<p>(A) No shift in the spectrum of a mixture of 3.0 µM metHb heme and 30 µM apo-N2 at the indicated times after mixing in a stopped-flow spectrophotometer. (B) Shift of absorption spectra after mixing 3 µM metHb heme with 30 µM apo-N2 and 30 µM NS-N1-MD. The arrows indicate the directions of the spectral shift during the reaction. (C) Time course of normalized spectral changes in the 3.0 µM metHb heme/30 µM apo-N2 reactions in the absence and presence of 30 µM NS-N1-MD. Black lines are the experimental data, and the dotted red lines are curves of fitting the metHb/N2/NS-N1-MD and metHb/N2 reactions data to single and double exponential equations, respectively. (D) Overlay of the absorption spectra of metHb/apo-N2 after 12-h incubation, holo-N2, and metHb/apo-N2/NS-N1-MD after 30-min incubation.