Hemoglobin/O2Systems: Using Short-lived Intermediates for Mechanistic Discrimination

Czerlinski, George; Levin, Richard I.; Ypma, Tjalling

doi:10.1006/jtbi.1999.0939

Cited by 2 publications

(13 citation statements)

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“…Un modèle complet du comportement de l'hémoglobine aété implémenté, en particulier faisant intervenir deuxétats allostérique des molécules d'hémoglobine. Ce modèle s'inspire de [4].…”

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Following red blood cells in a pulmonary capillary

Mauroy

2008

ESAIM: Proc.

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The red blood cells or erythrocytes are biconcave shaped cells and consist mostly in a membrane delimiting a cytosol with a high concentration in hemoglobin. This membrane is highly deformable and allows the cells to go through narrow passages like the capillaries which diameters can be much smaller than red blood cells one. They carry oxygen thanks to hemoglobin, a complex molecule that have very high affinity for oxygen. The capacity of erythrocytes to load and unload oxygen is thus a determinant factor in their efficacy. In this paper, we will focus on the pulmonary capillary where red blood cells capture oxygen. We propose a camera method in order to numerically study the behavior of the red blood cell along a whole capillary. Our goal is to understand how erythrocytes geometrical changes along the capillary can affect its capacity to capture oxygen. The first part of this document presents the model chosen for the red blood cells along with the numerical method used to determine and follow their shapes along the capillary. The membrane of the red blood cell is complex and has been modelled by an hyper-elastic approach coming from Mills et al (2004). This camera method is then validated and confronted with a standard ALE method. Some geometrical properties of the red blood cells observed in our simulations are then studied and discussed. The second part of this paper deals with the modeling of oxygen and hemoglobin chemistry in the geometries obtained in the first part. We have implemented a full complex hemoglobin behavior with allosteric states inspired from Czerlinski et al (1999).Comment: 17 page

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Following red blood cells in a pulmonary capillary

Mauroy

2008

ESAIM: Proc.

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“…We investigate the influence of this model of the mixing process on the kinetics of two previously studied reaction systems, namely (a) the glutamic aspartic aminotransferase system 9, (b) a modification of this system, and (c) the hemoglobin/O 2 system 10. While these systems are complex, our study shows that only the first few, relatively simple steps are relevant.…”

Section: Methodsmentioning

confidence: 96%

“… Reaction of molecular oxygen (O 2 or component 1) with (human) hemoglobin (Hb or component 2) adapted from Fig. 2 of Czerlinski et al 10 by moving the fast interconversion from the last complex to the first. …”

Section: Methodsmentioning

confidence: 99%

“…To investigate what could be accomplished with a more complex reaction system, we selected the reaction of (human) hemoglobin with molecular oxygen. We described this reaction previously 10, distinguishing between the two chains of hemoglobin (α and β). Figure 2 is a modification of Fig.…”

Section: Methodsmentioning

confidence: 99%

“…Figure 2 is a modification of Fig. 2 of our earlier paper 10, with the rate constants defined directly in the figure; rate constants k 2 j − 1 , with j = 1–8, are bimolecular, all others are monomolecular. Their values are listed in Table IV.…”

Section: Methodsmentioning

confidence: 99%

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The effect of the mixing process on reaction kinetics

Czerlinski

Levin

Ypma

2003

Int J of Chemical Kinetics

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If the chemical rate constants of the initial reaction steps are large, any observed value of these constants may be affected by the mixing process. To investigate the effect of mixing efficiency on reaction kinetics we use two previously analyzed reaction systems, namely the glutamic aspartic aminotransferase system and the hemoglobin/O 2 system. A time constant k a for the mixing process is introduced and four values for this parameter are considered, with the fastest essentially corresponding to complete mixing before any reaction can take place. The remaining three values are associated with mixing instruments, since they may be attainable in the real world. To evaluate the mixing efficiency (and conversely determine underlying k a values) from observed kinetics, mixing was combined with chemical relaxation by temperature jumps initiated at different points in time during the mixing process. Computer simulations permit the development of specific criteria to determine (in reverse) appropriate values of k a . In this respect, the aminotransferase system proved to be more revealing than the hemoglobin system.

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Hemoglobin/O2Systems: Using Short-lived Intermediates for Mechanistic Discrimination

Cited by 2 publications

References 8 publications

Following red blood cells in a pulmonary capillary

Following red blood cells in a pulmonary capillary

The effect of the mixing process on reaction kinetics

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