Hemoglobins from Wistar rat: crystallization of components and intraerythrocytic crystals.
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2,3-Diphosphoglycerate↗
Biomedical subjects
S G Condò
Publications and source records attributed to S G Condò.
The effect of pH and D-glycerate 2,3-bisphosphate on the O2 equilibrium of normal and SH(beta 93)-modified human hemoglobin.
The present paper reports data for the effect of pH and D-glycerate 2,3-bisphosphate (D-glycerate-2,3-P2) on the oxygen equilibrium of normal and SH(beta 93)-modified human hemoglobin. At sufficiently high D-glycerate-2,3-P2 concentrations, both oxy and deoxy forms of HbA are saturated with the organic phosphate at all pH values between 6 and 9. Furthermore the difference in the affinity for D-glycerate-2,3-P2 between deoxy and oxy hemoglobin remains constant with pH, implying that the pK values of the Bohr effect groups in deoxy and oxyhemoglobin are not affected by the presence of D-glycerate-2,3-P2 on the hemoglobin molecule. In the hemoglobins modified in position beta 93, the difference in affinity between deoxy and oxy hemoglobin for D-glycerate-2,3-P2 decreases with decrease in pH due mainly to a decrease in the affinity of the deoxy form for D-glycerate-2,3-P2. The effect of the chemical modification appears to be primarily a change in pK of a Bohr group in deoxy hemoglobin which is especially pronounced in the presence of phosphates.
2,3-Diphosphoglycerate↗
Purification and functional properties of the hemoglobin components from the rat (Wistar).
Homogeneous components of Wistar rat hemoglobin have been isolated and characterized from the molecular and functional point of view. The O2 equilibrium behaviour of the three main components (HbII, HbIII, HbIVA) has been investigated as a function of pH and organic phosphate concentration. The ligand-binding kinetics of the isolated components have been also studied and are fully consistent with their equilibrium behaviour. It should be remarked that the choice of the system was governed largely by the ability of rat hemoglobins to crystallize very quickly. This almost unique molecular property together with the complete reversibility of the process may allow information to be obtained on the thermodynamics of ligand-linked phase changes.
Animals↗
Functional properties of hemoglobins from Triturus cristatus.
The functional properties of hemoglobins from Triturus cristatus carnifex have been characterized both from an equilibrium and a kinetic point of view. A special attention has been given to the effect of organic phosphates in view of their role in the modulation of the hemoglobin function. Under stripped conditions newt hemoglobins display a negative Bohr effect which becomes much less pronounced in the presence of 0.2 M inorganic phosphates. The effect of organic phosphates involves not only a drop in the O2 affinity but also a large change in the shape of the O2 Bohr effect which becomes markedly positive in the presence of myo-inositol hexakis(phosphate). The experimental data reported make it possible to give a complete picture of the functional behaviour of newt hemoglobins, making a contribution to clarifying the dependence of the sign of the Bohr effect on the acclimatization temperature of the animals that has been previously reported [Morpurgo, G., Battaglia, P. A. and Leggio, T. (1970) Nature (Lond.) 225, 76--77].
Adenosine Triphosphate↗
Distribution and respiratory properties of sheep hemoglobins A and B containing the II alphaHis chain.
We recently reported the discovery of a second alpha chain, differing from the common alpha chain by the replacement 113 (or 114) Leucine leads to Histidine, in the hemoglobin of several domestic sheep. The ratio of the common alpha chain, here called alpha Leu, to the variant one, here called II alpha His, was either about 1.8:1 or about 4:1. In this study, the distribution of the II alpha His chain in 217 sheep from 8 domestic breeds was investigated: the II alpha His chain is present in 30% of animals from different breeds. Oxygen equilibrium determination showed no differences in the oxygen affinity, the Bohr effect and the heme-heme interaction of Hb A (alpha 2 beta 2A) and Hb B (alpha 2 beta 2B), each containing one of the three possible alpha chain phenotypes.
Animals↗
Evidence for multiple differing cation binding sites on hemoglobin A and S.
Some divalent cations (at 10(-3)M concentration) have been shown to act as oxygen-linked ligands. The effect of Ca++ (only on hemoglobin S) and Zn++ (on normal hemoglobin and hemoglobin S) can be traced to a preferential binding of these cations to the oxy- conformation of the proteins; the reverse is true for Ni++, since its presence reduces the oxygen affinity of both hemoglobins. The results suggest: i) the existence of at least two different cation binding sites on hemoglobin; ii) the replacement of glutamic acid by valine in hemoglobins S introduces sufficient structural modification to form a new cation binding site.
Binding Sites↗
The effect of 2-methoxy-5-nitrotropone on the oxygen affinity of human erythrocytes and hemoglobin.
Human hemoglobin reacted with 2-methoxy-5-nitrotropone at pH 7.4 undergoes modification of the four N-terminal amino groups. The modified protein shows increased oxygen affinity with complete abolition of the effect of K-glycerate 2, 3-bisphosphate. The Bohr effect is abolished in the acid range and drastically reduced at alkaline pH values. Changes in the kinetics of ligand reactions parallel the oxygen equilibrium results. Cooperative effects are still present. Human erythrocytes treated with 2-methoxy-5-nitrotropone show increased oxygen affinity and some decrease in methemoglobin reductase efficiency but no change in resistance to hemolysis.
Erythrocytes↗
Properties of trout hemoglobin covalently bound to a solid matrix.
This paper reports the ligand binding properties of the major hemoglobin component from trout (Salmo irideus) covalently bound to a solid matrix (Sepharose or Sephadex). A comparison between the functional properties of this protein in solution and of the protein-matrix complex shows significant changes although the basic properties of the molecule are maintained on covalent binding to Sepharose (or Sephadex). Thus the Root effect, characteristic of Hb trout IV, is still present while the heme-heme interactions are, on the average, smaller in the matrix bound protein as compared to the soluble form. No differences in the O2 binding properties were observed when the protein was coupled to the resin, as the ligand bound or as the ligand free derivative. Although an unequivocal interpretation of the data is made difficult by the lack of information on the number and identity of the groups involved in the coupling, the main changes in the protein functional properties may be related to the chemical modifications "per se" more than to the immobilization imposed to the macromolecule by coupling to the matrix. Structural changes which mainly involve perturbation of the tertiary structure of the molecule may qualitatively rationalize the data.
Animals↗
Intracellular distribution of organic phosphates in the rabbit erythrocyte and action on rabbit erythrocyte hexokinase.
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2,3-Diphosphoglycerate↗
[Necessity and validity of standard models for experimental preclinical evaluation of biomaterials. An example of biologic characterization of a hydroxyapatite-based implant material].
A large number of methods are now available for the preclinical screening of implantable materials concerning their biocompatibility and their ability to stimulate tissue formation. In vitro techniques represent a very useful tool, since this way we can realistically simulate the biological events which occur in vivo at the bone-implant interface. In the present study scanning electron microscopy and light microscopy observations were performed in order to assess the effect of an hydroxyapatite granulate on cell behaviour and morphology. Uptake of proteins to hydroxyapatite surface has been also investigated by comparing the amounts adsorbed after incubation with bovine serum albumin and bovine pancreaticamilase. According to our preliminary observation cells do not show signs of toxicity or inhibition of cell growth even after 14 days of co-culture with hydroxyapatite. Granules were covered by an uninterrupted cell layer by day seven. Even after two days micrographs show cells anchored and spread over the surface of the underlying granules, with a flattened and stellate shape. Such a morphology indicates a very high cellular activity, suggesting that the interaction with hydroxyapatite seriously increased metabolism. Measurements of protein adsorption on the hydroxyapatite surface show that changes in the size of particles affect the binding of proteins, while, in the case of granular hydroxyapatite, despite changes in size of granules, variations of protein adsorption were not observed, neither in relation to their different isoelectric point. Our preliminary results represent a good example of the opportunities presented by an experimental in vitro model.
Biocompatible Materials↗