One-dimensional and two-dimensional nuclear magnetic resonance studies of the reaction of phenyldichloroarsine with glutathione

14C-labeled phenyldichloroarsine (PDA) enters the red blood cell and forms a 1:2 adduct with intracellular glutathione. Upon gel filtration of the hemolysate, [14C]PDA was recovered with the glutathione-containing fractions. One-dimensional and two-dimensional nuclear magnetic resonance spectroscopy were used to confirm the structure of the adduct and elucidate its stereochemistry, stability, and reactivity.     

Effect of selenium on resistance of hemoglobin to photooxidative processes

On an example of a guinea pig it is shown that exogenous selenium (0.5 mg Na2SeO3 per 1 kg of the animal weight) during 2-hour exposition in the animal organism increases the resistance to the photo-induced oxidation of haemoglobin in erythrocyte lysates without additional stimulation of glutathione peroxidase mechanism of haemoglobin protection by exogenous selenium. It is shown that the saturation of haemoglobin fractions by selenium hampers the oxidative modification of haemoglobin. Using pregnancy of women as a natural model of selenium-deficiency condition, it has been shown that physiological debilitation of saturation erythrocytes with selenium, including haemoglobin fractions of lysates erythrocytes caused debilitation of resistance of haemoglobin to photooxidative destruction. Under these conditions not only activity of enzyme glutathione peroxidise in erythrocyte lysates, but also the peroxidase activity of haemoglobin (in the presence of glutathione) were decreased. It is more characteristic of erythrocyte lysates with a less content of selenium, i.e. for the erythrocytes of women on late terms of pregnancy that testifies to the presence of certain relation between haemoglobin saturation with selenium and its peroxidase activity (in the presence of glutathione).     

Susceptibility of erythrocytes from several animal species to Vibrio vulnificus hemolysin

The hemolytic activity of Vibrio vulnificus hemolysin (VVH) against erythrocytes from several animal species (sheep, horse, cow, rabbit, chicken) was investigated. VVH was active against erythrocytes from all species, but the amount of VVH causing 50% hemolysis under identical conditions (hemolytic susceptibility to VVH) differed. The degree of 125I-labeled VVH (125I-VVH) binding to each erythrocyte species correlated with the susceptibility of the cells to hemolysis. However, marked differences in the binding ability of 125I-VVH were not observed against liposomes constructed with lipids from each erythrocyte membrane. On the other hand, release of hemoglobin (Hb) differed for each of the erythrocyte species despite administration of approximately the same hemolytic VVH concentration to each species. Furthermore, under hypotonic conditions, the stability of each erythrocyte species varied markedly; the more susceptible the erythrocyte to VVH, the more unstable it was under such conditions. These results, therefore, suggest that the susceptibility of erythrocytes to VVH may be closely associated with the binding ability of VVH and erythrocyte membrane stability.     

Characterization of monoclonal antibodies that recognize band 4.5 polypeptides associated with nucleoside transport in pig erythrocytes.

Three monoclonal antibodies have been raised against partially purified band 4.5 polypeptides [Steck (1974) J. Cell Biol. 62, 1-19] from pig erythrocyte membranes. The antibodies were capable of binding to both intact pig erythrocytes and protein-depleted membrane preparations and recognized detergent-solubilized polypeptides from adult and neonatal pig erythrocytes that were photolabelled with [G-3H]nitrobenzylthioinosine (NBMPR), a potent specific inhibitor of nucleoside transport. The antibodies did not recognize polypeptides from neonatal pig erythrocytes that were photolabelled with the glucose-transport inhibitor [3H]cytochalasin B. Reactivity with polypeptides of apparent Mr 64,000 [10% (w/v) acrylamide gels] was demonstrated by Western-blot analysis. The antibodies recognized pig band 4.5 polypeptides after prolonged treatment with endoglycosidase F, a finding consistent with reactivity against polypeptide, rather than carbohydrate, determinants. Trypsin digestion of NBMPR-labelled protein-depleted pig erythrocyte membranes generated two labelled polypeptide fragments (Mr 43,000 and 26,000). Two of the antibodies recognized both fragments on Western blots, whereas the third bound to the larger, but not to the smaller, fragment. The antibodies had no significant effect on reversible binding of NBMPR to protein-depleted pig erythrocyte membranes and did not bind to NBMPR-labelled polypeptides in human, rabbit or mouse erythrocytes.     

Augmented water binding and low cellular water content in erythrocytes of camel and camelids.

We investigated a link between hemoglobin primary structure, hemoglobin hydrophobicity-hydrophilicity, and erythrocyte water content in various mammalian species. Some hemoglobin molecules, particularly those of the camel and camelids, contain more charged amino acid residues and are more hydrophilic than the hemoglobins of human and a number of other mammalian species. To test the in vivo significance of these alterations of hemoglobin primary structure, we determined the osmotically unresponsive erythrocyte water fractions in mannit solutions of various osmolarities at 4 degreesC. Among the species investigated, the size of the osmotically unresponsive erythrocyte water fraction relates in a positive linear way to hemoglobin hydrophilicity. The extreme low total erythrocyte water content of camel erythrocytes (1.1-1.3 g water/g dry mass) may be explained by a comparatively high osmotically unresponsive erythrocyte water fraction. It is proposed that alterations of hemoglobin sequences of camel and camelids may be the part of a natural selection process aimed at protecting these animals against osmotic dehydration in arid environments.     

Macromolecular covalent binding of [14C]nitrobenzene in the erythrocyte and spleen of rats and mice

Nitrobenzene exposure is known to produce red blood cell damage as well as engorgement and sinusoidal congestion of the spleen in male Fischer-344 (F-344) rats but not in male B6C3F1 mice. These studies were conducted to investigate the species differences in the covalent binding of [¹⁴C]nitrobenzene in the erythrocyte and spleen and to assess the contribution of nitrobenzene-induced erythrocytic damage to the splenic effects. Total and covalently bound ¹⁴C concentrations in erythrocytes of rats were 6–13 times greater than those of mice following a single oral dose of 75, 150, 200 or 300 mg/kg [¹⁴C]nitrobenzene, suggesting that species differences in nitrobenzene-induced red blood cell toxicity may be related to differences in erythrocytic accumulation of nitrobenzene and its metabolites. Covalently bound ¹⁴C in erythrocytes of rats peaked 24 h following administration of 200 mg [¹⁴C]nitrobenzene/kg; in contrast, bound radio-label in erythrocytes from mice plateaued at 10 h. Splenic engorgement increased in a time-related manner in treated rats but not in mice. Species specificity was also observed in the accumulation of bound radiolabel in the spleen. Gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of lysed, dialyzed erythrocytes from treated rats revealed that hemoglobin was the primary, if not the exclusive, site of macromolecular covalent binding following nitrobenzene treatment. SDS-PAGE of dialyzed rat spleens revealed that 82% of total bound ¹⁴C migrated identically to hemoglobin. These data indicate that covalent binding of [¹⁴C]nitrobenzene and its metabolites in the spleen is primarily derived from bound ¹⁴C from scavenged erythrocytes. Therefore, the species differences in splenic engorgement and accumulation of [¹⁴C]nitrobenzene may be related to differences in susceptibility to nitrobenzene-induced red blood cell damage.     

Isoenzyme patterns of glutathione transferases from mammalian erythrocytes

The occurrence of glutathione transferase isoenzymes in mammalian erythrocytes was investigated. The enzymes present in the hemolysates of human, horse, beef, pig, and sheep erythrocytes were purified by a column of GSH-linked epoxy-activated Sepharose 6B and subjected to an isoelectric focusing run in the pH range 3.5-10. Human and horse preparations were resolved in a single peak of activity centered at pH 4.6 and 5.9, respectively. Two forms with a maximum of activity at pH 4.9 and 7.0 and four with a maximum at pH 5.9, 6.5, 7.1, and 8.1 were separated from bovine and porcine erythrocytes. At least six forms ranging from pH 4.3 to pH 7.1 were present in the ovine preparation, the neutral contributing more than 90% of total activity. The subunit composition of affinity-bound fractions was studied by sodium dodecyl sulfate-gel electrophoresis. The analysis revealed that erythrocyte glutathione transferases are composed of subunits of identical molecular weights. This result suggests that the polymorphism existing in beef, pig, and sheep may be due to charge isomers. The erythrocyte glutathione transferases did not express selenium-independent GSH peroxidase activity.     

Influence of mouse age and erythrocyte age on glutathione metabolism.

In order to determine whether the biological age of a mouse influences erythrocyte metabolism and erythrocyte aging in vivo, blood samples were collected from male C57/BL6J mice of different biological ages ranging from mature (10 months) to "very old" (37 months). In the very old mouse, compared with the mature mouse, the erythrocyte survival time was decreased, erythrocyte densities were increased, the concentrations of total free thiol and reduced glutathione, and glutathione reductase activity were decreased. Erythrocytes were separated into different density (age) groups by phthalate ester two-phase centrifugation or by albumin density-gradient centrifugation. The density-age relationship of erythrocytes was established by pulse-labelling with 59Fe in vivo and by subsequent determinations of specific radioactivity of erythrocyte fractions of different densities prepared during a chase period of 60 days. The age of erythrocytes in mice of all ages was directly related to density. Also, in older erythrocytes compared with younger erythrocytes, decreased concentrations of total free thiol and reduced glutathione, and decreased glutathione reductase activity were observed. These were the lowest in the old erythrocytes of very old mice. These results in aging erythrocytes from aging mice suggest that the glutathione status the erythrocyte may be an index of aging, not only of the cell but also of the organism.     

The interaction of triethyltin with components of animal tissues

1. The distribution of triethyl[(113)Sn]tin chloride in the rat, guinea pig and hamster is not uniform, the highest concentrations being in rat blood and the liver of all three species. 2. Subcellular fractionation of rat liver, brain and kidney shows that triethyltin binds to all fractions to different extents. In the liver of the rat and guinea pig the supernatant fraction contains the largest amount and the highest specific concentration; this triethyltin is bound to a non-diffusible component. 3. Rat haemoglobin is responsible for the binding of triethyltin in rat blood (2 moles of triethyltin/mole of haemoglobin). Haemoglobins from other species have much less affinity for triethyltin. 4. A variety of other proteins do not bind triethyltin.     

Physiological effects of high-P50 erythrocyte transfusion on piglets

Rightward shifts of the O2 dissociation curve (ODC) were experimentally obtained in lysed and resealed erythrocytes following encapsulation of inositol hexaphosphate (IHP). This continuous lysing and resealing procedure led to in vitro P50 (Po2 at 50% hemoglobin saturation) increases up to 80 Torr (pH, 7.40; Pco2, 40 Torr; temp, 37 degrees C) for both human and pig erythrocytes. The Hill number of the transformed blood decreased when IHP was fixed on the hemoglobin, but the sigmoid shape of the ODC was maintained. The O2 hemoglobin binding capacity and the mean corpuscular hemoglobin content were found unchanged by the experimental procedure in human and pig erythrocytes. Isovolumic exchange transfusion of high-P50 erythrocytes in anesthetized and ambient air-ventilated piglets (n = 6) led to substantial in vivo P50 increases (range, 8-19 Torr). The rightward shift of the ODC was concomitant with an increase of the arterial Po2 and of the arteriovenous O2 content difference, 19 and 59% respectively above their control values. The mixed-venous Po2 (PVO2) remained unchanged. The cardiac output was shown to be inversely related to the P50 value. In spite of the O2-transport reduction (37%), O2 consumption was maintained due to enhanced O2 extraction.     

Comparative effects of phosphoenolpyruvate on selected mammalian erythrocytes

1. Incubation of human, rat, cow, sheep, dog, rabbit and monkey erythrocytes with phosphoenolpyruvate (PEP) resulted in increased intracellular 2,3-diphosphoglycerate (2,3-DPG). 2. Physiologic temperature (37 degrees C) and a pH less than 6.5 were required for transport and metabolism of PEP in rat and monkey erythrocytes. 3. Although erythrocytes from all species (except pig) exhibited PEP transport and metabolism, hemoglobin oxygen affinity (HOA) was affected only in species whose hemoglobins are sensitive to 2,3-DPG. 4. These results suggest that the effect of PEP incubation on HOA is mediated through 2,3-DPG.     

Human autologous rosette-forming cells. III. Binding of erythrocytes from different species to the T-cell receptors for autologous red blood cells

Spontaneous rosette formation in humans is restricted to a subpopulation of the circulating T cells. We have previously shown that the interaction between lymphocytes and autologous red blood cells (auto-RBC) is not mediated by a self-recognition mechanism, since allogeneic (allo-) RBC bind to T cells through the same receptors. In this work, we have extended these observations to thymocytes. Using a mixed-rosette assay in which one type of erythrocyte was identified by FITC labeling, we have shown that almost all the thymocytes which attached auto-RBC could also fix allo-RBC. However, as for the peripheral blood lymphocytes (PBL), binding of human RBC to thymocytes occurred with varying affinities according to the erythrocyte's origin. In order to further study the specificity of the erythrocyte to lymphocyte binding in rosette formation, PBL were mixed with auto-RBC and erythrocytes of xenogeneic (xeno-) origin. Although very disparate incidences of rosettes were found according to the species from which the RBC were derived, most of the autorosetting lymphocytes also had receptors for xeno-RBC. In addition, preincubation of PBL with monoclonal antibody OKT11A (directed against the sheep RBC receptors on T cells) completely abrogated rosette formation with all the erythrocytes tested (human auto- and allo-, sheep, pig, and rabbit) except mouse RBC. Taken together these data strongly suggest that human auto- or allo-, as well as sheep or some other xeno-RBC, bind to T lymphocytes by a single receptor and that the combining sites are expressed with different densities or varying affinities depending upon the RBC's origin. Therefore, spontaneous autorosettes may represent T lymphocytes having high-affinity receptors for sheep RBC.     

Hemin-induced lysis of rat erythrocytes. Protective action of ceruloplasmin and different serum albumins

Hemin-induced lysis of rat erythrocytes is markedly reduced by ceruloplasmin (human) and serum albumins from different species, the order of effectiveness beings: bovine albumin approximately equal to ceruloplasmin greater than human albumin approximately equal to dog albumin greater than apotransferrin (human). Although the proteins studied had hemin binding capacity, the best protective agents, ceruloplasmin and bovine albumin, did bind hemin less strongly than human and dog albumin. The results suggest the existence of another protective mechanism, possibly involving an interaction between erythrocyte membranes and serum proteins.     

Glutathione Synthesis and Turnover in the Human Erythrocyte: ALIGNMENT OF A MODEL BASED ON DETAILED ENZYME KINETICS WITH EXPERIMENTAL DATA

The erythrocyte is exposed to reactive oxygen species in the circulation and also to those produced by autoxidation of hemoglobin. Consequently, erythrocytes depend on protection by the antioxidant glutathione. Mathematical models based on realistic kinetic data have provided valuable insights into the regulation of biochemical pathways within the erythrocyte but none have satisfactorily accounted for glutathione metabolism. In the current model, rate equations were derived for the enzyme-catalyzed reactions, and for each equation the nonlinear algebraic relationship between the steady-state kinetic parameters and the unitary rate constants was derived. The model also includes the transport processes that supply the amino acid constituents of glutathione and the export of oxidized glutathione. Values of the kinetic parameters for the individual reactions were measured predominately using isolated enzymes under conditions that differed from the intracellular environment. By comparing the experimental and simulated results, the values of the enzyme-kinetic parameters of the model were refined to yield conformity between model simulations and experimental data. Model output accurately represented the steady-state concentrations of metabolites in erythrocytes suspended in plasma and the changing glutathione concentrations in whole and hemolyzed erythrocytes under specific experimental conditions. Analysis indicated that feedback inhibition of γ-glutamate-cysteine ligase by glutathione had a limited effect on steady-state glutathione concentrations and was not sufficiently potent to return glutathione concentrations to normal levels in erythrocytes exposed to sustained increases in oxidative load.     

Uptake of hexavalent chromium by bovine erythrocytes and its interaction with cytoplasmic components; The role of glutathione

Hexavalent chromium (Cr(VI)) anion gradually penetrated into bovine erythrocytes and bound with cytoplasmic components. Its penetration was strongly inhibited by the NH₂-reactive agent, 4-acetamido-4′-isothiocyano-stilbene-2,2′-disulfonic acid (SITS) and the SH-reactive agent, N-ethylmaleimide (NEM). Gel filtration showed that the intracellular component that bound to chromium was hemoglobin.

The binding affinity of Cr(VI) to hemoglobin in the absence of glutathione in vitro was found to be much less than in intact erythrocytes. However, in the presence of glutathione, the binding affinity of Cr(VI) to hemoglobin became much higher. This indicates that reduction of hemoglobin or Cr(VI) by glutathione is involved in the binding.

Cr(VI) interacted only weakly with the membrane and did not cause hemolysis of bovine erythrocytes, unlike heavy metals such as Hg²⁺.     

In vitro kinetics of oxygen transport in erythrocyte suspension or unmodified hemoglobin solution from human and other animals

Oxygen transport behavior in erythrocyte suspension or in hemoglobin solution was studied as a potential therapeutic model for the clinical treatment of blood loss, and this can also provide physiological data with which to evaluate blood substitutes. In the present project, we examined the in vitro kinetics of hemoglobin binding to and releasing oxygen, to provide detailed oxygen-flux measurements for unmodified hemoglobin solutions and erythrocyte suspensions in human, as well as other vertebrates. An in vitro method was used, based on a widely used artificial system, with the oxygen saturation level being detected in real time. Results from this study indicated that the kinetic curves of human erythrocyte suspensions and hemoglobin solutions were either S-shaped or hyperbolic, respectively. Based on these curves, the significance of T(50) emerged in our investigation, where T(50) is defined as the time needed for 50% hemoglobin to be saturated with oxygen, and reflects the efficiency with which hemoglobin carries oxygen. This parameter may be used to diagnose blood diseases, and could be a standard for evaluating blood substitutes. In this study, we also compared the T(50) of 4 species of vertebrates, and found that it shows a distinct efficiency of oxygen binding related to species, and potentially reveals the evolutionary function of hemoglobin and its possible adaptation to the environment.     

Synaptic and extra-synaptic distribution of histamine H1-receptors in rat and guinea pig brains

Localization of histamine H1-receptors in subcellular fractions from rat and guinea pig brains was examined in a [3H]mepyramine binding study. Major [3H]mepyramine binding sites with increased specific activities [( 3H]mepyramine binding vs. protein amount) were recovered from P2 fractions from both rat and guinea pig brains by differential centrifugation. Further subfractionation of both rat and guinea pig P2 fractions by a discontinuous sucrose density gradient centrifugation showed the highest recovery of [3H]mepyramine binding with further increased specific activities found in synaptic plasma membrane (SPM) fractions. Minor [3H]mepyramine binding sites with increased specific activities were detected in both rat and guinea pig P3 fractions. [3H]Mepyramine binding sites in SPM and P3 fractions showed identical Kd values in each species. These results indicate that histamine H1-receptors are located not only in synaptic but also in extra-synaptic membranes of both rat and guinea pig brains.     

Partial reversible inactivation of enzymes due to binding to the human erythrocyte membrane

Summary Hypotonic human erythrocyte ghosts, devoid of the original glyceraldehyde-3-phosphate dehydrogenase content of the red cell, bind added glyceraldehyde-3-phosphate dehydrogenases, isolated from human erythrocytes, rabbit and pig muscle, as well as rabbit muscle aldolase. There are only slight differences in the affinities towards the various glyceraldehyde-3-phosphate dehydrogenases. On the other hand, glyceraldehyde-3-phosphate dehydrogenases are bound much stronger than aldolase; in an equimolar mixture the former can prevent the binding of the latter, or replace previously bound aldolase at the membrane surface. Binding is always accompanied by the partial inactivation of enzymes, which can be reverted by desorption. Unwashed ghosts rich in hemoglobin seem to have a more pronounced inactivating effect on bound glyceraldehyde-3-phosphate dehydrogenase. In isotonic media ghosts, whether white or unwashed, reseal and do not interact with the enzymes.     

A proton nuclear magnetic resonance study of the binding of methylmercury in human erythrocytes

The binding of methylmercury, CH₃Hg(II), by small molecules in the intracellular region of human erythrocytes has been studied by ¹H-NMR spectroscopy. To suppress or completely eliminate interfering resonances from the much more abundant hemoglobin protons, spectra were measured by a technique based on the transfer of saturation throughout the envelope of hemoglobin resonances following a selective presaturation pulse or by the spin-echo Fourier transform method. With these techniques, ¹H-NMR spectra were measured for the more abundant intracellular small molecules, including glycine, alanine, creatine, lactic acid, ergothioneine and glutathione, in both intact and hemolyzed erythrocytes to which CH₃Hg(II) had been added. The results for intact erythrocytes indicate that part of the CH₃Hg(II) is complexed by intracellular glutathione. These results also indicate that exchange of CH₃Hg(II) among glutathione molecules is fast, with the average lifetime of a CH₃Hg(II)-glutathione complex estimated to be less than 0.01 s. From exchange-averaged chemical shifts of the resonance for the proton on the α-carbon of the cysteine residue of glutathione, it is shown that, in hemolyzed erythrocytes, the sulfhydryl group of glutathione binds CH₃Hg(II) more strongly than the sulfhydryl groups of hemoglobin.     

Interaction of the 140/130/110 kDa rhoptry protein complex of Plasmodium falciparum with the erythrocyte membrane and liposomes

During Plasmodium falciparum merozoite invasion into human and mouse erythrocytes, a 110-kDa rhoptry protein is secreted from the organelle into the erythrocyte membrane. In the present study our interest was to examine the interaction of rhoptry proteins of P. falciparum with the erythrocyte membrane. It was observed that the complex of rhoptry proteins of 140/130/110 kDa bind directly to a trypsin sensitive site on intact mouse erythrocytes, and not human, saimiri, or other erythrocytes. However, when erythrocytes were disrupted by hypotonic lysis, rhoptry proteins of 140/130/110 kDa were found to bind to membranes and inside-out vesicles prepared from human, mouse, saimiri, rhesus, rat, and rabbit erythrocytes. A binding site on the cytoplasmic face of the erythrocyte membrane suggests that the rhoptry proteins may be translocated across the lipid bilayer during merozoite invasion. Furthermore, pretreatment of human erythrocytes with a specific peptide derived from MSA-1, the major P. falciparum merozoite surface antigen of MW 190,000-200,000, induced binding of the 140/130/110-kDa complex. The rhoptry proteins bound equally to normal human erythrocytes and erythrocytes treated with neuraminidase, trypsin, and chymotrypsin indicating the binding site was independent of glycophorin and other major surface proteins. The rhoptry protein complex also bound specifically to liposomes prepared from different types of phospholipids. Liposomes containing PE effectively block binding of the rhoptry proteins to mouse cells, suggesting that there are two binding sites on the mouse membrane for the 140/130/110-kDa complex, one protein and a second, possibly lipid in nature. The results of this study suggest that the 140/130/110 kDa protein complex may interact directly with sites in the lipid bilayer of the erythrocyte membrane.