ISSN:
1573-4943
Keywords:
Hemopexin
;
heme
;
circular dichroism
;
spectroscopy
;
CO-binding
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract Hemopexin binds 1 mol of heme per mol with high affinity (K d 〈 1 pM) in a low-spin complex and acts as a transport vehicle for the heme. Circular dichroism (CD) spectroscopy was used to examine the heme environment in the ferri-, ferro-, and CO-ferro complexes of four iron tetrapyrroles [meso-, proto-, deutero-, and (2-vinyl, 4-hydroxymethyl)-deutero-heme] with three species (human, rabbit, and rat) of hemopexin. All ferri-heme-hemopexin complexes exhibit a band of positive ellipticity near the Soret maximum, except for the human ferri-protoheme hemopexin complex, which has a bisignate spectrum. The ferro-heme and CO-ferro-heme complexes display a variety of spectra, demonstrating redox- and ligand-linked shifts in conformation that alter the environment of the heme. The rabbit mesoheme-N-domain complexes have absorbance spectra almost indistinguishable from those of intact hemopexin, but present CD spectra that are distinctly different. However, adding the C-domain to mesoheme-N-domain restores most of the CD characteristics of the intact hemopexin complexes.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1007016105813
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