Journal article
Iron Porphyrin Phenoxides: Models for Some Hemoglobin Mutants
Journal of the American Chemical Society, Vol.100(24), pp.7585-7591
01 Nov 1978
Abstract
Variously substituted phenoxides (L) reacted with [Fe(PPIXDBE)]20 (PPIXDBE is the protoporphyrin IX di-tert-butyl ester dianion) to produce 5-coordinate high-spin complexes Fe(PPIXDBE)L which displayed spectroscopic properties similar to those of the Met form of the .alpha. mutant chain of [human] HbM Boston. The addition of pyridine or 1-methylimidazole (L'') to Fe(PPIXDBE)L at 77.degree. K produced low-spin 6-coordinate complexes Fe(PPIXDBE)LL'' which were studied spectroscopically. With the strongly basic 2,6-dimethoxyphenoxide (L), the above reaction was studied at 298.degree. K, where for L'' = 1-methylimidazole the binding constant was approximately 100 M-1 in CH2Cl2. The Fe(PPIXDBE)LL'' complexes were made in an attempt to mimic the Fe(III) in the .alpha. chain of Met HbM Iwate. The latter was high spin. With excess p-nitrophenoxide in CH2Cl2, Fe(PPIXDBE) (OC6H4-4-NO2) formed Fe (PPIXDBE) (OC6H4-4-NO2)2-, which exhibited a high-spin EPR spectrum at 77.degree. K. Addition of phenoxides or fluoride to Fe(II) protoporphyrin ester systems produced species such as Fe(PPIXDBE)X22- (X = OR or F), similar to those found previously with methoxide and hydroxide ions. The addition of CO to a bisphenoxy species, in Me2SO, resulted in a splitting of the Soret Band at 438 nm into 2 bands at 434 and 413 nm, which were attributed, respectively, to a carbonyl (phenoxide) species and a carbonyl species which contains no phenoxide. The visible spectral data supported the view expressed by others that upon reduction of HbM Iwate at pH 6.5 by Na2S2O4 the iron-tyrosine bond was broken.
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Details
- Title
- Iron Porphyrin Phenoxides: Models for Some Hemoglobin Mutants
- Creators
- E W Ainscough - University of British ColumbiaA W Addison - University of British ColumbiaD Dolphin - University of British ColumbiaB R James - University of British Columbia
- Publication Details
- Journal of the American Chemical Society, Vol.100(24), pp.7585-7591
- Publisher
- Amer Chemical Soc
- Number of pages
- 7
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Chemistry
- Identifiers
- 991022027636804721