Absorption spectra of sperm-whale ferrimyoglobin

Abstract

1. Sperm-whale ferrimyoglobin was found to contain 0.308% of Fe, on a dry weight basis, corresponding to a molecular weight of 18130. The solid takes up moisture to an equilibrium state, and was then assayed to contain 0.280% of Fe. 2. Absorption spectra are presented for acidic ferrimyoglobin, Fe(+)(H(2)O), and its conjugate base, Fe-OH, as well as for the fluoride and cyanide complexes, within the range 200-2500mmu. Data for ferromyoglobin-carbon monoxide, Fe(II)-CO, in the visible region are also included. 3. Minor spectral differences have been found between whale and horse myoglobins, particularly in the effect of temperature on the visible-absorption spectrum of Fe-OH.

The role of the heme distal ligand in the post-translational modification of Synechocystis hemoglobin

“…Above pH 9 the features changed gradually toward those of an alkaline solution of ferric heme. Within the 5-9 pH range, no significant spectral change was observed, which showed that the weak 624-nm band was not due to a contribution of a high-spin His/H 2 O species in rapid equilibrium with a His/OH À form [39].…”

Denaturant dependence of equilibrium unfolding intermediates and denatured state structure of horse ferricytochrome c

“…The cyanide derivative of horse heart metmyoglobin (Mb-CN) was prepared by mixing a slight molar excess of sodium cyanide (Sigma) with a 3.0 mM solution of horse heart metmyoglobin (Sigma) in 50 mM sodium phosphate buffer (NaP i ) in D 2 O. Cyanide binding was confirmed by the shift of the Soret band in the absorption spectrum from 409 to 422 nm. The concentration of protein samples was determined using an extinction coefficient of 106,100 L mol -1 cm -1 at 410 nm (Fe(III) h-cyt c) [24], 104,000 L mol -1 cm -1 at 408 nm (Fe(III) t-cyt c) [25], or 116,000 L mol -1 cm -1 at 422 nm (Mb-CN) [26].…”

NMR investigation of ferricytochrome c unfolding: Detection of an equilibrium unfolding intermediate and residual structure in the denatured state

“…The pH* was readjusted to 7.0 after mixing, and the Soret band shift to 422 nm confirmed complete cyanide binding. The concentration was measured by using an extinction coefficient of 116,000 liters͞mol-cm at 422 nm (24).…”