Hemoglobin oxygenation, table

We may also estimate the value of K49 directly from the experimental data of Stadie and O Brien in a way which obviates the need of neglecting the effect of the hemoglobin. In Table VI of their paper Stadie and O Brien list measured values of pH for each of the values of pCO studied, both for the oxygenated and deoxygenated solutions. From these values we may obtain K49 at once by means of the equation of electrical neutrality as given above, namely... 

Fig. 1.3. Correlation between the Hill parameter and partial oxygen pressure at half saturation for chemically modified and mutant hemoglobins from Table 1. hemoglobins modified at a subunits o hemoglobins modified at P subunits. Curves represent calculated values obtained by varying the parameters a (curve a) and the parameter b (curve b), introduced as described in the text. Parameters used in the calculation are four parameters of the AE as given in Fig. 1.1, and five parameters of the GAE S = 0.6...

Pyridoxal Derivatives. Various aldehydes of pyridoxal (Table 3) react with hemoglobin at sites that can be somewhat controlled by the state of oxygenation (36,59). It is thereby possible to achieve derivatives having a wide range of functional properties. The reaction, shown for PLP in Figure 3, involves first the formation of a Schiff s base between the amino groups of hemoglobin and the aldehyde(s) of the pyridoxal compound, followed by reduction of the Schiff s base with sodium borohydride, to yield a covalendy-linked pyridoxyl derivative in the form of a secondary amine. 

Similarly, iron is an essential mineral in hemoglobin that is required to transport oxygen. It is also an essential nutrient in bone marrow, liver, and spleen. Iron deficiency, for example, in cases of anemia, is therefore routinely supplemented with ferrous sulfate or a variety of other iron-based compounds. If its supplementation is not urgent, it can also be replenished by adapting iron-rich diets. Prescribed iron supplements feature in the top 200 most prescribed dmgs in the United States only in 2004 (Table 1.17). 

Oxygenation curves of hemoglobin are often fitted with the Adair equation (Eq. 7-12). Thus, at pH 7.4 under the conditions given in Table 7-2, Imai125 found for the successive formation constants Kj = 0.004, K2 = 0.009, K3 = 0.002 and fQ = 0.95 in units of mm Hg 1. From the definition of a formation constant the oxygen... 

In order to calculate the standard transformed Gibbs energies of formation of the four oxygenated forms of hemoglobin, we need the value of AfG° for molecular oxygen in aqueous solution at 21.5°C. The NBS Table (1992) indicates that ArG0(O2(ao)) = 16.1 kJ mol-1 at 21.5°C. The value of ArG 0(T(O2)) is calculated using... 

Extinction coefficients, mM, in parentheses data for Hb from Ref. 1 for chelated protoheme from Ref. 26 and 30. c See Table I for hemoglobin references the oxygen rates are the average of the a and j3 chains. The chelated protoheme rates are from Ref. 26 and 30. 

Macromolecules often have a number of sites for interactions and binding of the solute or ligand molecules. For example, hemoglobin in the blood binds oxygen at certain sites. Surface charges on the molecules also affect the diffusion. Therefore, the presence of macromolecules and small solute molecules in solutions may affect Fickian-type diffusion. Most of the experimental data on protein diffusivities have been extrapolated to very dilute or zero concentration since the diffusivity is often a function of concentration. Table 6.4 shows diffusivities of some proteins and small solutes in aqueous solutions. The diffusion coefficients for the macromolecules of proteins are on the order of magnitude of 5 X 10 11 m2/s. For small solute molecules, the diffusivities are around 1 X 10 9 m2/s. Thus, macromolecules diffuse about 20 times slower then small molecules. 

Many metals are essential to plant and animal life, although in many cases their role is uncertain. The list includes all the first-row transition metals except scandium and titanium, but only molybdenum and perhaps tungsten from the heavier transition metals. Table 16-1 lists several that are important in mammalian biochemistry. The importance of iron is obvious from the number of roles it plays, from oxygen carrier in hemoglobin and myoglobin to electron carrier in the cytochromes to detoxifying agent in catalase and peroxidase. 

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