RESUMO
The 1H-NMR spectra and the resonance Raman spectra of intermediate spin complex, octaethylporphyrinatoiron (III) perchlorate (OEP-Fe(III)ClO4) and its mono imidazole adduct have been recorded and analyzed. The perchlorate complex was determined to be an intermediate-spin state (S = 3/2) in dichloromethane. The mono imidazole and 2-methylimidazole adducts of OEP-Fe(III)ClO4 were of the high-spin state in dichloromethane, which is a good model for the ferrihemoproteins such as metmyoglobins. The spin state of OEP-Fe(III)ClO4 varies the polarity of solvent from typical high-spin (S = 5/2) to typical low-spin (S = 1/2) state including intermediate-spin state (S = 3/2). The resonance Raman studies of the intermediate-spin complex in various solvents indicate that the complex is a plausible model to reproduce anomalous physico-chemical properties of the ferricytochrome c' at physiological condition.
Assuntos
Heme , Hemina , Imidazóis , Grupo dos Citocromos c , Espectroscopia de Ressonância de Spin Eletrônica , Heme/análogos & derivados , Espectroscopia de Ressonância Magnética , Modelos Químicos , Percloratos , Solventes , Análise Espectral RamanRESUMO
Sperm whale apomyoglobin was recombined with 2,4-diisopropyldeuterohemin to form 2,4-diisopropyldeuteroheme-myoglobin and its various physico-chemical properties were investigated to get an insight into the structural and functional role of the peripheral vinyl groups. 2,4-Diisopropyldeuteroheme-myoglobin showed a four times lower oxygen affinity at 25 degrees C and larger enthalpy and entropy changes of oxygenation than the corresponding values of native myoglobin. 2,4-Diisopropyldeuteroheme-metmyoglobin shows a pKa value of 9.68 which is higher than those of native metmyoglobin and mesoheme-metmyoglobin. The rate of autooxidation of oxy-form was about seven times larger in 2,4-diisopropyldeuteroheme-myoglobin than in native myoglobin. The electron-donating effect of isopropyl groups does not give straightforward explanation for these anomalous properties of 2,4-diisopropyldeuteroheme-myoglobin. It is proposed that site and stereospecific van der Waals' interaction between the polypeptide side chains and the peripheral 2,4-diisopropyl groups may weaken the interaction between the bound oxygen molecule and the distal His, resulting in the decrease in the stability of oxyform.
Assuntos
Deuteroporfirinas , Mioglobina , Oxigênio , Porfirinas , Animais , Heme/análogos & derivados , Hemina/análogos & derivados , Concentração de Íons de Hidrogênio , Cinética , Metamioglobina , Oxirredução , Pressão Parcial , Ligação Proteica , Espectrofotometria , BaleiasRESUMO
A chromoprotein from Pleurotus salmoneostramineus L. Vass. has been purified and crystallized. The needle-shaped crystal has monoclinic space group C2 with the cell dimensions of a = 118.5, b= 59.7,0 c = 31.8 A and beta = 114 degrees. The crystal diffracts to 1.8 A resolution with a synchrotron radiation X-ray source.