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Spectroscopic studies have provided extensive information on the primary process of visual pigments and photoexcitation of chlorophyll as well as their effects on photoreactivity on the higher-order structures of protein has been observed only rarely. Resonance Raman spectroscopy can reveal the vibrational frequencies of the chromophore in a molecule provided the excitation wavelength is in the absorption band of that molecule. As the visible absorption bands of haemproteins are due to pi pi* transitions of the porphyrin ring, we can selectively observe the vibrational frequencies of iron porphyrin during in situ interactions with immediate amino acid residues of protein when the wavelength of excitation light is close to the Soret or Q band. Correlation of some vibrational frequencies of haem with the oxidation and spin states of the haem iron has been studied in detail and an empirical rules has been established. This method is therefore especially suitable for the study of an effect of higher-order structures of protein on the chromophore. We report here a photoreaction facilitated by a particular quaternary structure of protein--in various haemoglobins resonance Raman spectroscopy showed that reversible photoreduction of haem took place in the T state but not the R state. 相似文献
577.
Levamisole added to cultured calvarial bones inhibited spontaneous bone resorption, as indicated by reduced release of calcium and inorganic phosphate to the medium. In addition, levamisole reduced lactate production and release of lysosomal enzymes. 相似文献
578.
Single crystals of oxycobalt-myoglobin were examined by electron paramagnetic resonance (EPR) spectroscopy at ambient and cryogenic temperatures. The principal values and eigenvectors of the g-tensor and the hyperfine coupling tensor were determined. The Co--O--O bond angle was estimated to be 125 degrees at ambient temperature. The single crystal EPR dats of oxycobalt myoglobin at 77K showed two sets of the principal values for g and hyperfine coupling tensors and eigenvectors, indication that the bound oxygen molecule takes two distinct orientations. The result has demonstrated for the first time that the well defined change in the molecular orientation is induced upon freezing the biological macromolecule. 相似文献
579.
Summary Bovine pancreatic deoxyribonuclease (DNase I) was immobilized on human erythrocytes with several procedures. DNase immobilized on the erythrocytes by chromic chloride showed DNase activity in vitro. Other binding procedures inhibit the immobilized DNase activity. 相似文献
580.