Chromium-51 labeling of sheep red blood cells.

The failure of sheep red blood cells (RBCs) labeled with Chromium-51 (Cr-51) using the ascorbic acid technique to act as a suitable intravascular marker of blood volume in a septic sheep model prompted us to investigate the technique of radiolabeling sheep erythrocytes with this isotope. Consequently, we studied thirteen sheep in which the labeling efficiency of Cr-51 as sodium chromate and hemoglobin typing was determined for each animal. Mean Cr-51 labeling efficiency of sheep RBCs was 67.5% (n = 13). Although 5 of the 13 sheep were discovered to have two types of hemoglobin (Hb) as determined by electrophoresis, overall labeling efficiency of sheep RBCs was determined to be independent of the type of hemoglobin present. However, when two types of Hb were present (Hb-A and Hb-B), Cr-51 had a higher affinity for Hb-B (80%) than Hb-A (20%) even though both Hb types are present in similar proportions (Hb-A = 53%, Hb-B = 46%). The results of this study indicate that sheep RBCs express a lower labeling efficiency for Cr-51 than do human RBCs and that Cr-51 has a higher affinity for Hb-B than for Hb-A when both hemoglobin types are present. This difference is noteworthy when interpreting Cr-51 RBC data in experimental sheep models. Furthermore, caution should be exercised when extrapolating established human protocols to animal models.     

Electrophoretic characterization of the hemoglobins in pocket gophers of the genus Thomomys.

1. Hemoglobin phenotypes have been determined for closely related pocket gopher subspecies in the genus Thomomys from sea level and high altitude. 2. A single hemoglobin band was demonstrated for each gopher population with cellulose acetate membrane electrophoresis, with a mobility of 73% relative to human Hb-A. 3. Using polyacrylamide gel electrophoresis, a major Hb component (94% of the total Hb) showed a relative mobility of 68-69%; the minor Hb component showed a relative mobility of 74-75%. 4. The electrophoretic and physiological similarities of the gopher hemoglobins have persisted despite extreme differences in ambient PO2 in the habitats of each subspecies.     

Functional behaviour of dilute solutions of Hb-Kempsey: beta 99 (G-1) Asp--Asn.

The authors report that a diluted solution of Hb-Kempsey, beta 99 (G-1) Asp-Asn, can be chromatographically separated from the coexistent Hb-A and functionally examined if progressively depleted in O2 by bubbling pure nitrogen in the solution. Next, at fixed times, the O2 saturations of Hb are compared with the pO2s measured. Hb-Kempsey has a p50 of 1 torr, with an n-value of 1 and a Bohr effect of -0.2. Normal Hb-A of the same patient, examined with identical methods, presents: p50 = 4.5 torr; n = 2.7; Bohr effect = -0.412. Therefore, Hb-Kempsey is strongly hyperaffinic, does not display any heme-heme interaction, and has a half-normal Bohr effect.     

Quantitative assessment of hemoglobin-induced endothelial barrier dysfunction.

Hemoglobin (Hb)-based O2 carriers (HBOC) are undergoing extensive development as potential "blood substitutes." A major problem associated with these molecules is an increase in microvascular permeability and peripheral vascular resistance. In this paper, we utilized bovine lung microvascular endothelial cell monolayers and simultaneously measured Hb-induced changes in transendothelial electrical resistance, diffusive albumin permeability, and diffusive Hb permeability (PDH) for three forms of Hb: natural tetrameric human Hb-A and two polymerized recombinant HBOCs containing alpha-human and beta-bovine chains designated Hb-Polytaur (molecular mass: 500 kDa) and Hb-(Polytaur)n (molecular mass: approximately 1,000,000 Da), respectively. Hb-Polytaur and Hb-(Polytaur)n are being evaluated for clinical use as HBOCs. All three Hb molecules induce a rapid decline of transendothelial electrical resistance to 30% of baseline. Diffusive albumin permeabiltiy increases, on average, approximately ninefold (2.78 x 10(-7) vs. 2.47 x 10(-6) cm/s) in response to Hb exposure. All three Hb molecules induce an increase in their own permeability, a process that we have called Hb-induced Hb permeability. The magnitude of change of PDH is also related to Hb size. When PDH is corrected for the diffusive coefficient for each Hb species, no evidence of restricted diffusion is found. Immunofluorescent images demonstrate Hb-induced actin stress fiber formation and large intercellular gaps. These data provide the first quantitative assessment of the effect of polymerized HBOC on their own diffusion rates over time. We discuss the importance of these findings in terms of Hb extravasation rates, molecular sieving, and clinical consequences of HBOC use.     

Characteristics in tyrosine coordinations of four hemoglobins M probed by resonance Raman spectroscopy

Resonance Raman spectra of four hemoglobins (Hbs) M with tyrosinate ligand, that is, Hb M Saskatoon (beta distal His----Tyr), Hb M Hyde Park (beta proximal His----Tyr), Hb M Boston (alpha distal His----Tyr), and Hb M Iwate (alpha proximal His----Tyr), were investigated in order to elucidate structural origins for distinctly facile reducibility of the abnormal subunit of Hb M Saskatoon in comparison with other Hbs M. All of the Hbs M exhibited the fingerprint bands for the Fe-tyrosinate proteins around 1600, 1500, and 1270 cm-1. However, Hb M Saskatoon had the lowest Fe-tyrosinate stretching frequency and was the only one to display the Raman spectral pattern of a six-coordinate heme for the abnormal beta subunit; the others displayed the patterns of a five-coordinate heme. The absorption intensity of Hb M Saskatoon at 600 nm indicated a transition with a midpoint pH at 5.2, whereas that of Hb M Boston was independent of pH from 7.2 to 4.8. The fingerprint bands for the tyrosinate coordination as well as the Fe-tyrosinate stretching band disappeared for Hb M Saskatoon at pH 5.0, and the resultant Raman spectrum resembled that of metHb A, while those bands were clearly observed for Hb M Boston at pH 5.0 and for two Hbs M at pH 10.0. These observations suggest that the unusual characteristics of the heme in the abnormal beta chain of Hb M Saskatoon result from the weak Fe-tyrosinate bond, which allows weak coordination of the proximal histidine, giving rise to the six-coordinate high-spin state at pH 7.(ABSTRACT TRUNCATED AT 250 WORDS)     

Hemoglobin Koya Dora: high frequency of a chain termination mutant.

Approximately 10% of the members of the Koya Dora tribe from Andhra Pradesh (India) carry an alpha chain hemoglobin variant, Hb Koya Dora (Hb KD), usually in amounts of 0.5%-2% of total hemoglobin. In four presumed homozygotes for Hb KD, up to 10% of the abnormal hemoglobin was present. The alpha chain of Hb KD was found to be elongated by at least 16 residues, possibly as a result of a mutation of the normal alpha chain termination codon UAA TO UCA, coding for serine. A pedigree in which two individuals possess Hb KD as well as the alpha chain variant Hb Rampa and normal Hb A proves the existence of two alpha chain loci in this population. Hb DK resembles the previously described Hb Constant Spring [6, 7] in many aspects, probably also in its alpha thalassemia-like expression.     

Reduction of methemoglobins M Hyde Park, M Saskatoon, and M Milwaukee by ferredoxin and ferredoxin-nicotinamide adenine dinucleotide phosphate reductase system

The reduction of hemoglobins (Hb) M such as Hb M Iwate, Hb M Boston, Hb M Hyde Park, Hb M Saskatoon, and Hb M Milwaukee by the ferredoxin and ferredoxin-NADP reductase system was studied systematically under anaerobic conditions. The enzyme system could not reduce the abnormal chains in methemoglobin M with an alpha chain anomaly but effectively converted the methemoglobin M with a beta chain anomaly to the fully reduced form. During the reduction of the methemoglobin M with a beta chain anomaly, the spectra showed a shift of the initial isosbestic points, indicating the possible formation of intermediate hemoglobins in the partially reduced state. On the reduction mode of the methemoglobin M, however, it was classified into three types. 1) Only normal chains were reduced (Hb M Iwate and Hb M Boston). 2) Sequential reduction from normal to abnormal chains occurred (Hb M Milwaukee and Hb M Hyde Park). 3) Normal chains were preferentially reduced, but the reduction of abnormal chains also started at the same rate when the reduction of normal ones had proceeded halfway (Hb M Saskatoon). These differences are discussed in relation to the redox potential of each abnormal chain in methemoglobin M.     

Heme structures of five variants of hemoglobin M probed by resonance Raman spectroscopy

The alpha-abnormal hemoglobin (Hb) M variants show physiological properties different from the beta-abnormal Hb M variants, that is, extremely low oxygen affinity of the normal subunit and extraordinary resistance to both enzymatic and chemical reduction of the abnormal met-subunit. To get insight into the contribution of heme structures to these differences among Hb M's, we examined the 406.7-nm excited resonance Raman (RR) spectra of five Hb M's in the frequency region from 1700 to 200 cm(-1). In the high-frequency region, profound differences between met-alpha and met-beta abnormal subunits were observed for the in-plane skeletal modes (the nu(C=C), nu(37), nu(2), nu(11), and nu(38) bands), probably reflecting different distortions of heme structure caused by the out-of-plane displacement of the heme iron due to tyrosine coordination. Below 900 cm(-1), Hb M Iwate [alpha(F8)His --> Tyr] exhibited a distinct spectral pattern for nu(15), gamma(11), delta(C(beta)C(a)C(b))(2,4), and delta(C(beta)C(c)C(d))(6,7) compared to that of Hb M Boston [alpha(E7)His --> Tyr], although both heme irons are coordinated by Tyr. The beta-abnormal Hb M variants, namely, Hb M Hyde Park [beta(F8)His --> Tyr], Hb M Saskatoon [beta(E7)His --> Tyr], and Hb M Milwaukee [beta(E11)Val --> Glu], displayed RR band patterns similar to that of metHb A, but with some minor individual differences. The RR bands characteristic of the met-subunits of Hb M's totally disappeared by chemical reduction, and the ferrous heme of abnormal subunits was no longer bonded with Tyr or Glu. They were bonded to the distal (E7) or proximal (F8) His, and this was confirmed by the presence of the nu(Fe-His) mode at 215 cm(-1) in the 441.6-nm excited RR spectra. A possible involvement of heme distortion in differences of reducibility of abnormal subunits and oxygen affinity of normal subunits is discussed.     

Location of amino acid substitutions in human hemoglobin. Mass spectrometric rapid analysis of tryptic peptides

Point mutations alpha 58 His----Tyr (Hb M Boston), beta 6 Glu--lys (Hb C) and beta 26 Glu----Lys (Hb E) have been identified in abnormal hemoglobins by means of tryptic hydrolysis of their alpha- and beta-chains followed by mass-spectrometry coupled with direct extraction of ions from solution. The abnormal hemoglobin Hb M Boston alpha 58 (E7) His----Tyr has been for the first time found in the blood of a patient from the USSR. This express-method is generally applicable for the identification of point mutation in proteins. The amount of protein necessary for the analysis is 100-1000 pmole. The stability, proteolytic degradation of the identified abnormal Hb's and Hb Bart's were investigated. The molecular pathogenesis of the hemoglobinopathies are discussed from the point of view of the observed properties.     

Site-directed mutagenesis in hemoglobin: functional and structural role of inter- and intrasubunit hydrogen bonds as studied with 37 beta and 145 beta mutations.

In order to clarify the functional and structural role of intra- and intersubunit hydrogen bonds in human hemoglobin (Hb A), we prepared two artificial beta chain mutant hemoglobins by site-directed mutagenesis. The mutant Hb Phe-37 beta, in which Trp-37 beta is replaced by Phe to remove the intersubunit hydrogen bond between Asp-94 alpha and Trp-37 beta at the alpha 1-beta 2 interface in deoxy Hb A, showed a markedly increased oxygen affinity and almost completely diminished Bohr effect and cooperativity. However, 1H-NMR data indicated that the structure of deoxy Hb Phe-37 beta is rather similar to that of deoxy Hb A. The enhanced tetramer-to-dimer dissociation previously observed in Hb Hirose (Trp-37 beta----Ser) together with our observation of the effects of organic phosphate on the structure and function of Hb Phe-37 beta suggested that a large part of the abnormal properties of Hb Phe-37 beta observed for dilute solutions appears to result from partial dissociation into alpha beta dimers rather than direct destabilization of the T-quaternary structure in the deoxygenated state. Thus, the primary and direct role of the hydrogen bond between Asp-94 alpha and Trp-37 beta is to stabilize the tetrameric assembly, and thereby this hydrogen bond indirectly contributes to stabilization of the T-quaternary structure. The other mutant Hb Phe-145 beta has a Phe residue at the 145 beta site and lacks the intrasubunit hydrogen bond formed between Tyr-145 beta and the carbonyl group of Val-98 beta in deoxy Hb A.(ABSTRACT TRUNCATED AT 250 WORDS)     

Structural study of hemoglobin Hazebrouck, beta 38(C4)Thr----Pro. A new abnormal hemoglobin with instability and low oxygen affinity

A new beta-variant has been detected and structurally defined in a French male, with a life-long history of hemolytic anemia. This variant is moderately unstable and has a low oxygen affinity. The abnormal hemoglobin was not detected by standard electrophoretic procedures. It moved slightly slower than Hb A during isoelectric focusing (IEF). Two minor fractions were also seen; the first migrated just cathodal to Hb F, as did partially oxidized Hb A or hemichrome derivatives of some unstable hemoglobins; the second in the position of free alpha-chains. The abnormal beta-chain was readily separated from both beta A- and alpha A-chains by acid-urea-Triton globin chain electrophoresis. Structural study was conducted simultaneously by fingerprinting and high-performance liquid chromatography (HPLC) of tryptic peptides. A new mutation beta 38(C4)Thr----Pro was found, which was named Hb Hazebrouck.     

beta-Thalassaemia with increased haemoglobin A2 in Turkey. A study of 164 thalassaemic heterozygotes.

Clinical and haematological findings of 164 Turkish beta-thalassaemic heterozygotes with increased Hb-A2 are presented. The series comprised of 19 children, 81 females and 64 males. The majority of these thalassaemic individuals were asymptomatic and only 4 of them had slight or moderate splenomegaly. The mean values of haemoglobin concentration, PCV, MCH and MCHC were significantly lower than those of the corresponding normal controls. Erythrocytosis was present in 33% of them. Hb-A2 values ranged between 3.8 and 6.1%, and between 3.8 and 6.5% as assessed by the methods of DEAE- or DE-cellulose chromatography, respectively. Hb-F was found to be above the normal range in 15.1%. It is established that beta-thalassaemia with increased Hb-A2 is the most frequent variety of thalassaemia in Turkey (80%) and both beta+- and beta0-thalassaemia genes were present in this country. The regional distribution of beta-thalassaemia in Turkey is also presented and the origin of beta-thalassaemia genes in Turkish people is discussed.     

Ethylisocyanide equilibria of hemoglobins M Iwate, M Boston, M Hyde Park, M Saskatoon, and M Milwaukee-I in half-ferric and fully reduced states.

The ethylisocyanide equilibria of all the five known hemoglobins M, namely Hb M Iwate (alpha287 Tyrbeta2), Hb M Boston (alpha258 Tyrbeta2), Hb M Hyde Park (alpha2beta292 Tyr), Hb M Saskatoon (alpha2beta263 tyr), and Hb M Milwaukee-I (alpha2beta267 Glu), were studied both in the half-ferric and fully reduced heme states. In the half-ferric state, no heme-heme interaction was observed for Hb M Iwate, Hb M Boston, and Hb M Hyde Park, but Hb M Saskatoon and Hb M Milwaukee-I show small but definite heme-heme interaction with Hill's n of 1.3. The beta chain mutants, Hb M Hyde Park and Hb M Saskatoon, have almost normal affinity for ethylisocyanide and a normal Bohr effect, whereas the alpha chain mutants, Hb M Iwate and Hb M Boston, have abnormally low affinity and almost no Bohr effect. Hb M Milwaukee-I showed a large Bohr effect and low affinity. These results are consistent qualitatively with those on oxygen equilibria reported previously. In the fully reduced state, in which all four hemes were in the ferrous state and capable of binding ethylisocyanide distinct differences were found in the extent of heme-heme interaction. Namely, the n values for proximal histidine mutants, Hb M Iwate and Hb M Hyde Park, were 1.1 and 1.0, respectively, whereas the distal histidine mutants, Hb M Boston and Hb M Saskatoon, showed high n values of 2.4 and 1.6, respectively. Hb M Milwaukee-I also exhibited a high n value of 2.0 The ethylisocyanide affinity of the four histidine mutants was high compared with that of Hb A, while that for Hb M Milwaukee-I was almost normal. All five Hbs M had approximately normal magnitudes of Bohr effect. In the half-ferric state, the proximal and distal histidine mutants of the same chain showed similar affinity for ethylisocyanide and Bohr effect, rather different from those of the mutants of the opposite chain. These differences seem to be derived from the difference of abnormal bonding of ferric iron to tyrosine or glutamic acid. On the other hand, the reduction of iron, which abolished the abnormal bonding and made all of the chains capable of binding ligand, extinguished the differences of alpha and beta chains, and the effect of amino acid side chains close to iron on ligand binding properties became clear. Proximal histidine, which is considered to trigger the transition between the T and R states, seems to be essential to the heme-heme interaction.     

Complete deoxygenation from a hemoglobin solution by an electrochemical method and heat treatment for virus inactivation

Hemoglobin (Hb) has been widely studied as a raw material for various types of oxygen carriers. In the purification of Hb from red blood cells including virus inactivation and denaturation of other proteins and the long-term storage of Hb vesicles (HbV), a deoxygenation process is one of the important processes because of the high stability of deoxygenated Hb to heating and metHb formation. Though an oxygenated Hb solution can be deoxygenated with an artificial lung, it is difficult to reduce the oxygen partial pressure of the Hb solution to less than 10 Torr. We developed an electrochemical system for complete deoxygenation of the Hb solution at the cathode compartment using hydrogen containing nitrogen gas at the anode compartment. Oxygen in the Hb solution was reduced to OH(-) at the cathode compartment within several minutes at a potential value of -1.67 V and was finally converted to water by neutralization with H(+) from the anode in the whole system. The resulting completely deoxygenated Hb could tolerate heat treatment at 62 degrees C for 10 h with no denaturation of deoxygenated Hb. The metHb formation rate of reoxygenated Hb at 37 degrees C was not changed after heat treatment. Furthermore, vesicular stomatitis virus (VSV) could be inactivated at an inactivation degree of more than 5.96 log by heat treatment.     

Hemoglobin calais [β 76 (E20) Ala → pro]: a hemoglobin variant with decreased intrinsic oxygen affinity

Hb Calais [β 76 (E20) Ala → Pro] is a new human hemoglobin variant displaying a decreased oxygen affinity. The only electrophoretical difference with Hb A was a slight more acidic isoelectric point. A 2-fold decrease in the oxygen affinity was found by equilibrium measurements performed in a suspension of intact red blood cells and in the lysate. It was confirmed by kinetic studies of the purified abnormal hemoglobin. The rte of methamoglobin formation at 37°C of Hb Calais was also increased realtive to Hb A. The mechanism by which the Pro for Ala substitution of an external residue in the β-chains results in these profound functional abnormalities is nuclear. Subtle changes at the heme pocket, at a distance from teh mutation, may be a plausible explanation for the effects observed.     

Hemoglobin G San José {\text{[}}\beta _{\text{2}} {\text{(A4)Glu}} \to {\text{Gly}}\alpha _{\text{2}} {\text{],}}β thalassemia,and α thalassemia in a sicilian family

A 3-year-old child of Sicilian origin was found to have a severe form of Cooley's anemia. Investigations were extended to other members of her family. In three, a rare beta-chain structural Hb variant, Hb G San José [beta 7 (A4) Glu to Gly], was observed: in the father of the porposita heterozygosity for the abnormal Hb was found to be coexistent with beta o thalassemia; two sisters had lowered MCV and MCH values and levels of the abnormal Hb significantly lower than in other heterozygotes for Hb G San José. The alpha-chain/total beta-chain synthesis ratios suggest an alpha-thalassemic-like effect. Their mother had lowered MCV and MCH values, an Hb A2 level in the upper limit of the normal range, and a balanced alpha-chain/beta-chain synthesis ratio. Therefore, the possibility of coexistence of an alpha thalassemia trait with a beta thalassemia trait in the mother of the proposita and with Hb G San José heterozygosity in the two sisters who had lowered levels of abnormal Hb is discussed.     

Three cases of hemoglobin O Arab.

Three new cases of Hb 0 Arab in two families are reported from districts of Bulgaria, where a carrier state of this abnormal hemoglobin has not been established so far. One of the propositi is a double heterozygote for Hb 0 Ar/beta(0)-thalassemia. His father is a simple heterozygote for Hb 0 Ar with clear-cut cytomorphological stigmata, indicating hemoglobinosis. The second propositus, according to clinical and laboratory data is also a double heterozygote for Hb 0 Ar and beta(0)-thalassemia. The carriers investigated are of Bulgarian nationality. Their territorial origin supportsthe thesis that the gene mutation for Hb 0 Arab most probably has taken place out of the present boundaries of Bulgaria.     

Microscopic and spectroscopic study of the corona formation and unfolding of human haemoglobin in presence of ZnO nanoparticles

The interaction of zinc oxide nanoparticles (ZnO NPs) with human haemoglobin (Hb) is studied for the biologically safe application of ZnO NPs in the human body. The Hb corona is formed around the ZnO nanoparticles, directly observed from high‐resolution transmission electron microscopy (HRTEM) images. Hb formed ‘hard corona' on the surface of ZnO NPs from an exponential association mechanism over a very short duration, as well as unfolding of Hb that occurred over a long lifetime. Dynamic light scattering measurements demonstrated that the ZnO NPs were completely covered by Hb with shell thickness of c. 6 nm that formed a ‘hard corona'. Zeta potential measurements represented that the ZnO NPs were fully covered by Hb molecules using an exponential association mechanism. Tryptophans (TRY), as well as heme‐porphyrin moieties of Hb, are the major binding sites for ZnO NPs. The nature of the interaction between ZnO NPs and Hb was analysed from the fluorescence quenching of TRYs. Electrostatic interaction, along with the hydrophobic interaction between ZnO NPs and Hb, is responsible for the conformational change in Hb due to increase in the percentage of β‐sheets together with a decrease in α‐helices.     

Sequencing and comparative analysis of the lux operon of Photorhabdus luminescens strain ZM1: ERIC elements as putative recombination spots

The EcoRI chromosomal fragment (6782 bp) containing the lux operon of Photorhabdus luminescens was cloned in pUC18 and completely sequenced. Enteric repetitive intergenic consensus (ERIC), an imperfect palindrome (125-127 bp) characteristics for Enterobacteriaceae genomes, was found in three sites. Strain Zm1 proved to differ in ERIC number and location from strains Hb, Hm, and Hw. Nucleotide substitution analysis showed that luxC and luxB, which are more than 1 kb away from ERIC, are similar to the corresponding Hb genes, whereas luxD, luxA, and luxE, which are close to ERIC, are intermediate between their Hb and Hw counterparts. The Hb/Hw nucleotide substitution ratio was 1:1 in regions adjacent to ERIC. Hence ERIC were assumed to play a role of recombination hot spots in the bacterial genome.     

Increased susceptibility of malaria-infected variant erythrocytes to the mononuclear phagocyte system

The interactions of the mononuclear phagocyte system with Plasmodium falciparum-infected genetically variant erythrocytes may result in a significant protection for the host. Infected hemoglobin (Hb) EE and Hb EA erythrocytes are more susceptible to phagocytosis by monocytes than are infected Hb AA erythrocytes. The increased susceptibility to phagocytosis of infected erythrocytes was also found for a number of genetic variants involving the alpha-globin chain, namely, alpha-thal 1 trait (--/alpha alpha), alpha-thal 2 trait (-alpha/alpha alpha), Hb H (--/-alpha), Hb H/Hb Constant Spring (CS) (--/alpha CS alpha), Hb CS trait, and homozygous Hb CS erythrocytes. In addition, oxidative damage from hydrogen peroxide, produced in simulation of macrophages, led to much more effective killing of parasites in glucose-6-phosphate dehydrogenase (G6PD)-deficient erythrocytes than in normal ones. Parasites infecting Hb H/Hb CS also showed an enhanced sensitivity to hydrogen peroxide.