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Myoglobin dimer

Myoglobin is a protein of molecular weight of about 17,000 with the protein chain containing 153 amino acid residues folded about the single heme group. This restricts access to the iron atom (by a second heme) and reduces the likelihood of formation of a hematin-like Fe(III) dimer. The micro environment is similar to that in Cytochrome c, but there is no sixth ligand (methionine) to complete the coordination sphere of the iron atom. Thus there is a site to which a dioxygen molecule may reversibly bind. [Pg.95]

Some dimeric myoglobins have been isolated from the muscles of the sea-snail Nassa mutabilis ind from the clams Anadora broughtonii and A. senilis. These have no Bohr effect but show ooperative effects for the uptake of 02.1274... [Pg.689]

In chemistry, it is well known that O2 can be strongly bound to a ferrons iron porphyrin in solvents without any protein matrix however, the oxygenated states of most simple iron porphyrins are irreversibly converted into /r-oxodimers (eqnation3), PFe(III)-0-PFe(III), via peroxo and ferryl intermediates (eqnation 2). The /x-oxodimer is usually very stable in solvents, so it is sometimes called a thermodynamic sink. In addition, autoxidation of PFe(II)-02 to an inert ferric porphyrin easily occurs under aerobic conditions (equation 4). Thus, it is clear that the heme pockets of myoglobin and hemoglobin play an important role in protecting the 02-bound heme from dimerization and autoxidation. [Pg.1871]

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... 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...
One of the representative models is the picket fence iron porphyrin reported by Coltman and his coworkers (Figure 4). The picket fence porphyrin as a structural model for myoglobin has four bulky pivaloyl groups at the peripheral positions to prevent two of these iron porphyrins from coming together to form a /u.-oxo dimer. The first significant result in their study was to demonstrate the 3D structure of the stable... [Pg.1873]

Figure 2. Utility of PE membrane over a large mass range. Spectra of bovine insulin (0.4 pmol/mm ), horse heart myoglobin (0.4 pmol/mm ), and bovine serum albuimin dimer (1 pmol/mm ) are displayed from top to bottom. All spectra are the summation of 20 shots, and are unsmoothed. Figure 2. Utility of PE membrane over a large mass range. Spectra of bovine insulin (0.4 pmol/mm ), horse heart myoglobin (0.4 pmol/mm ), and bovine serum albuimin dimer (1 pmol/mm ) are displayed from top to bottom. All spectra are the summation of 20 shots, and are unsmoothed.
Figure 16.25 Experimental breakthrough curves of myoglobin on an immobilized metal affinity column (dotted line) and model calculations as a dimerizing system (solid line). Reproduced with permission from R. D. Whitley, K. E. van Cott, J. A. Berninger, N.-H. L. Wang, AIChE J., 37 (1991) 555 (Fig. 2). Figure 16.25 Experimental breakthrough curves of myoglobin on an immobilized metal affinity column (dotted line) and model calculations as a dimerizing system (solid line). Reproduced with permission from R. D. Whitley, K. E. van Cott, J. A. Berninger, N.-H. L. Wang, AIChE J., 37 (1991) 555 (Fig. 2).

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