Oxygen binding mechanism

Although low-resolution difference Fourier maps for oxy-Hr and deoxy-Hr show little change in the protein structures, some of the iron center properties are significantly altered in deoxy-Hr. The differences provide a rationale for an oxygen-binding mechanism. The Mossbauer spectrum for deoxy-Hr has a single quadrupole doublet with an isomeric shift typical of high-spin ferrous iron (8 = 1.14 mm/sec AEq = 2.76 mm/sec) (Clark and Webb, 1981). As for met-Hr the two iron environments are similar, yet differ in coordination number for exam-... 

MECHANISM FOR REVERSIBLE BINDING OF DIOXYGEN AND COOPERATIVITY OF OXYGEN BINDING... 

Oxygen binding to a metal can be represented by models sketched on Scheme 5, and it is understandable that the two atoms of the oxygen molecule linked to two metal atoms of the surface (bridge) is the most favorable position for weakening the 0—0 bond, leading to its dissociation. Recent ab initio calculations (DFT) have shown that the (111), (100), and (110) surfaces of Pt have different properties for the adsorption of O2, O, OH, OOH, and H2O2, which should influence differently the mechanism of ORR [39]. 

Figure 6.18. Trends in oxygen reduction activity plotted as function of the oxygen binding energy (adapted from Ref. [117]). Solid line associative mechanism arrows rate determining processes dashed line associative mechanism.

Hemoglobin has been a favorite protein molecule for designing and testing various models of the molecular basis of subunit interactions in multisubunit proteins. In the 1960s, two mechanisms were advanced to account for the sigmoidal nature of the oxygen binding curve for Hb A, one proposed by Monod et al. (1965) based on a... 

Areas of biomimetic chemistry relating to enzyme systems that function both with and without the benefit of coenzymes are included. Special emphasis has been placed on the following subjects vitamin Bi2 and flavins oxygen binding and activation bioorganic mechanisms and nitrogen and small molecule fixation. 

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