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Myoglobin denaturation, table

A titration curve for sperm whale myoglobin has been reported by Bres-low and Gurd (1962). The most striking feature is that it exhibits a time-dependent acid denaturation, which resembles that observed for the similar protein hemoglobin. To elucidate the physical nature of this reaction, emphasis was placed on the back titration to neutral pH of denatured protein. As in the case of hemoglobin (mentioned earlier), there are two major differences between the titration curves of native and denatured myoglobin, as shown by the data of Table XV. [Pg.149]

In contrast to Me cyts bs, the thermodynamic equilibrium ratio of A B isomers of 1 1.3 in OM cyt bs favors isomer B, and is obtained only after hours at 65 °C. At physiological temperature, the OM cyt bs heme is kinetically trapped. Several other properties of rat OM cyt bs differ from those of rat Me cyt bs. - (i) OM cyt bs has a significantly lower redox potential than Me cyt bs (Table 2) (ii) OM cyt bs T, 83.6 °C) is more stable toward thermal denaturation than Me cyt bs (7m, 65.2 °C). (iii) OM cyt bs is about lOkJmol ( 2.5kcalmol ) more stable than Me cyt bs towards chemical denaturation (iv) while bovine Me cyt bs will release heme to apo-myo obin at pH 7.0, heme is not transferred from rat OM cyt bs to apo-myoglobin even at pH values as low as 5.2. Two hydrophobic networks responsible for the stability and slow heme dissociation and reorientation in OM cyt bs have been identified. Mutation of the five residues involved in these hydrophobic networks in OM cyt bs yields a protein with the structural elements of Me cyt bs Molecular dynamics simulations predict two conformers of Me cyt bs in solution, a cleft-open and a cleft-closed form and only one, the cleft-closed form, for OM cyt Z>5.3 2 394 is proposed that OM cyt bs is held in the cleft-closed conformation by one of its hydrophobic networks. [Pg.46]


See other pages where Myoglobin denaturation, table is mentioned: [Pg.437]    [Pg.902]    [Pg.28]    [Pg.150]    [Pg.505]    [Pg.185]    [Pg.299]    [Pg.37]    [Pg.631]    [Pg.313]   
See also in sourсe #XX -- [ Pg.197 ]




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