Hemoglobin oxygenation

We can determine quantitatively the physiological significance of the sigmoid nature of the hemoglobin oxygen-binding curve, or, in other words, the biological importance of cooperativity. The equation... 

Chapter 11. Hemoglobin Oxygen Bonding and Magnetic Properties 849... 

Regulator mechanisms of hemoglobin oxygen affinity in acidosis and alkalosis. J Clin Invest (1971), 50,... 

Y. Nomura and M. Tamura. Quantitative analysis of hemoglobin oxygenation state of rat brain in vivo by picosecond time-resolved spectrophotometry. Journal of Biochemistry, 109 455-461, 1991. 

Alessandri, B., Qian, Y., Di, X., and Bullock, R. Reducing hemoglobin oxygen affinity does not increase hydroxyl radicals after acute subdural hematoma in the rat./. Neurotrauma 1999, 16, 123-133. 

Where equals the number of sites determined by some other biophysical procedure, we say that the system shows infinite cooperativity. No such behavior has been rigorously demonstrated for an enzyme or receptor. In the case of hemoglobin oxygenation (Fig. 2) under physiologic conditions, the Hill coefficient has a value of about 2.8. Of course, from X-ray structural information, we know that hemoglobin has four sites. Thus, we... 

Oxygen-Binding Proteins—Hemoglobin Oxygen Transport... 

The structure of glycerate-2,3-bisphosphate, an allosteric effector for hemoglobin oxygen release. 

Two quite different models were proposed about 25 years ago to explain the unusual nature of the hemoglobin oxygen-binding curve (fig. 5.14). These models can also be used as a starting point for discussing other allosteric proteins. The first model, introduced by Jacque Monod, Jeffery Wyman, and Pierre Changeux in 1965, is called the symme-... 

Finlay JC, Foster TH. Recovery of hemoglobin oxygen saturation and intrinsic fluorescence with a forward-adjoint model. Applied Optics 2005, 44, 1917-1933. 

Heroin and methadone produced a rapid and dramatic reduction in both respiratory rate and cortical hemoglobin oxygenation, while saline had no effects. The authors suggested that opioid-induced acute deoxygenation of cortical hemoglobin was probably associated with respiratory depression. In one in three subjects, oxygen saturation after intravenous heroin fell rapidly, a finding that has not previously been described in humans. 

The following simple reaction system has some of the characteristics of the hemoglobin-oxygen system that is much more complex because four molecules of oxygen are bound by the tetramer and the tetramer is partly dissociated. The system discussed here is like myoglobin except that myoglobin does not have a Bohr effect. 

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