Kinetic mechanism of the holoShr-to-apoShp heme transfer reaction.

<p>(<b>A</b>) Spectral shift in heme transfer from holoShr to apoShp. Absorption spectra of 0.8 µM holoShr are presented as a function of time for its reaction with 10 µM apoShp. The arrows indicate the directions of the spectral shift with time. (<b>B</b>) Time course of −ΔA₄₁₄ in the holoShr/apoShp reaction of panel A. The symbols and line are the observed data and theoretical line obtained by fitting the data to a two-exponential equation. (<b>C</b>) The observed rate constants <i>k</i>_t1obs and <i>k</i>_t2obs plotted as a function of [apoShp] in the holoShr-apoShp reaction. The rate constants at different [apoShp] were obtained from double-exponential fitting as in B.