Myoglobin deoxy, structure

Fig. 3.2 The structure of myoglobin (deoxy form, PDB entry 1AGN, at 1.15 A resolution [3f]). The heme active center is highlighted (van der Waals spheres), as are the proximal and distal histidines (His93 and His64, respectively, shown as sticks).

X-ray crystallographic structures of myoglobin and hemoglobin were first completed in 19662 and 19753, respectively. Since then, many other X-ray crystallographic studies of deoxy- and oxy- as well as met-myoglobin and hemoglobin have been carried out.22,24 Additionally, researchers have studied the carbon monoxide bound moieties MbCO and HbCO as well as MbNO. Site-directed mutagenesis of residues near the active sites of Mb and Hb have yielded... 

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...

IVXH. Yang, F, Phillips Jr., G. N., Structures of Co-, Deoxy- and met-Myoglobins at Various Ph Values. To be published. 

The structure of the picket-fence porphyrin compound, Fe(PF)(2-MeIm), is shown in Figure 4.28. Minus the pickets, it is essentially a magnified view of the active site of deoxy myoglobin, shown in Figure 4.29. Some metrical details of these structures, of a very similar unsubstituted tetraphenylpor-phyrin,"° and of several other deoxyhemoglobins are listed in Table... 

Neutron experiments were first made on haemoglobin [98,99,147,166,167] and were extended to myoglobin [44,168], lysozyme [169] and catalase [170] as models of typical globular proteins. In parallel with X-ray scattering, the haemoglobin work (mainly in H20) identified a conformational change between the oxy- and deoxy-forms which was reflected in an difference of 0.054 nm in H20 buffers. Scattering curve comparisons to <2 = 3 nm with the crystal structures verified this. 

Haem electronic structure in deoxy myoglobin Acid-alkaline transition in ferric myoglobin Oxy and carbonmonoxy myoglobins F relaxation mechanism... 

The ferry 1-Fe" is slowly reduced to the met-form. If the globin structures of deoxy-, oxy-or met-forms of myoglobin are disturbed, they are reversibly or irreversibly converted into hemochrome-Fe + or hemichrome-Fe. The role of these denatured species in lipid oxidation of meat is not clear. When ferric hemin is detached from the globin, the ferryl ion can initiate lipid oxidation by hydrogen abstraction to produce a lipid radical plus a proton. Iron can also be released from hemin in the presence of hydroperoxides to participate in lipid oxidation processes. Ascorbic acid and other reducing compounds in muscle cytosol effectively inhibit lipid oxidation promoted by ferryl ions in membranes. 

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