Deoxymyoglobin Myoglobin

The NMR spectra for the different electronic configurations described for myoglobin were also studied for hemoglobin and for the isolated -and -chains (Shulman et al. (99)). The basic spectral features are similar to those of the corresponding myoglobins, but the size of the hyperfine shifts of the heme resonances is quite different. As an illustration the resonances at low fields of deoxymyoglobin and deoxyhemoglobin are compared in Fig. 31. 

The dynamic state of sperm-whale myoglobin monitored by spin, fluorescence, and Mossbauer labels (Likhtenshtein, 1988, 1993) as a function of temperature was compared with the results ofkinetic studies on the photodissociation and reassociation of CO-deoxymyoglobin (Frauenfelder et al, 1991). The three independent labelling methods showed sharp increases in nanosecond mobility in the vicinity of the label in a temperature region of approximately 200-220 K. These temperatures were close to the temperatures of the dramatic increases in the relative quantum yield of the photodissociation, as well as to the fraction of non-dissociated molecules for 10"2 s... 

Figure 1 Three-dimensional structures of myoglobin and hemoglobin. (a) Deoxymyoglobin from sperm whale (1A6N) and (b) deoxy-hemoglobin from human (IBZO). Black and gray stick molecules are protoheme-lX. Hemoglobm consists of two af dimers, dark and light gray pairs...

This equation for the saturation of myoglobin gives a hyperbolic curve for the oxygenation of deoxymyoglobin (Fig. 6.5), very similar to the hyperbolic curve found for enzymes that follow the Michaelis-Menten equation (Chapter 7). 

On the other hand, our studies with myoglobin indicate that there is little or no chromate oxidation of deoxymyoglobin since ... 

Figure 7.14. Stereo view of the crystal structure of myoglobin in space-filling representation with a white protein chain, except for black non-His aromatic residues, and gray heme ligand with propionate oxygens shown as light atoms on gray heme at upper center of structure. (A) Deoxymyoglobin (Protein Data Bank, Structure...

When deoxyhemoglohin crystals are exposed to oxygen, they shatter. On the other hand, deoxymyoglobin crystals are unaffected hy oxygen. Explain. (Myoglobin is made up of only one of the four subunits, or polypeptide chains, of hemoglobin.)... 

---