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Query: UNIPROT:Q0Z944 (hemoglobin)
 63,986 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Changes in plasma haptoglobin, total protein, hematocrit, and hemoglobin content of blood were studied in rats at various times during a 7-d exposure to oxygen at 760 torr. Plasma haptoglobin and other plasma proteins were fractionated and quantitatively evaluated for a 3-d exposure period. Total protein and haptoglobin were depressed after 7 d of exposure. Significant changes were not noted before this time. With a 3-d exposure, for which plasma proteins were fractionated, fibrinogen showed a considerable increase whereas albumin, gamma globulins, and the beta 1 globulin fraction decreased significantly. Individual variations in albumin and haptoglobin were correlated inversely to the hematocrit. These variations indicate that the altered composition of the plasma protein is due, in part, to a variable loss of the various plasma protein fractions as a result of increased vascular permeability.
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PMID:Changes in haptoglobin and other plasma proteins of rats during exposure to pure oxygen at 760 torr. 111 9

1. Some of the individual members of the polymeric series of proteins from human haptoglobin types 2-1 and 2-2 were isolated by gel electrophoresis. By reacting this purified material with less than an equivalent amount of hemoglobin and analyzing the result by electrophoresis, the number of haptoglobin-hemoglobin complexes could be clearly counted. For the haptoglobin 2-1 series, the number of complexes formed was n+1, where n is the serial order, in decreasing electrophoretic mobility, of the haptoglobin polymeric form used. For the haptoglobin 2-2 series, the number of complexes was n+2. 2. For the first three members of haptoglobin 2-1 series, the haptoglobin-hemoglobin composition of the complexes was estimated from scans of the unstained gels. The data indicated that this series consists of 2,3,4... alpha beta haptoglobin subunits, each of which can combine with an alpha beta subunit of hemoglobin.
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PMID:Hemoglobin binding by isolated polymeric proteins from human haptoglobin types 2-1 and 2-2. Some suggested polymer subunit compositions. 113 84

We developed an assay for methemalbumin in biological fluids by using diethylaminoethyl-Sephadex ion-exchange chromatography to separate this protein from interfering components, including hemopexin, transferrin, hemoglobin, and haptoglobin/hemoglobin complex. Initial screening of the samples requires measurement of A280/A405 ratios of the peak tubes of the isolated albumin fraction. Values exceeding 30 indicate that methemalbumin is absent, and no further work is required. Values of less than 30 suggest that methemalbumin is present in the original sample, whereupon the presence and amount of methemalbumin can be ascertained by coloremetric assay for iron with use of ferrozine. Results may be expressed either in terms of micrograms of methemalbumin iron per gram of albumin or in milligrams of methemalbumin per liter. The reproducibility of the method is of the order of +/- 7% (SD). Normal persons have essentially no methemalbumin iron in their serum. Three individuals with hemorrhagic pancreatitis showed values of 65, 98, and 198 mug of methemalbumin Fe per gram of albumin.
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PMID:Clinical determination of methemalbumin. 115 22

Dimethyl adipimidate was used to cross-link the polypeptides within hemoglobin, haptoglobin, and hemoglobin-haptoglobin complex. Cross-linked hemoglobin retained considerable ability to bind haptoglobin, although the amounts bound were reduced and the haptoglobin reaction could be used to fractionate the modified hemoglobin. With cross-links limited to intramolecular sites, hemoglobin showed four bands on polyacrylamide gel electrophoresis in sodium dodecyl sulfate, identified, with reference to the subunit polypeptides, as monomer, dimer, trimer, and tetramer. The dimer region consisted of at least two separable species. When hemoglobin-haptoglobin complex was cross-linked, a band of hemoglobin dimer was present, which demonstrates that at least two hemoglobin subunits have a close spatial relation when bound to haptoglobin. Some comparisons with adipimidate-reacted hemoglobin were made using malonimidate and suberimidate and some marked differences were noted.
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PMID:Cross-linking of hemoglobin, haptoglobin, and hemoglobin-haptoglobin complex with bifunctional imidoesters. 118 Oct 7

The reaction rate analyzer LKB 8 600 is used in a new haptoglobin evaluation method. This technique involves formation of peroxidatic complex between haptoglobin and horse or human hemoglobin (human hemoglobin is easier to prepare), then oxidation of gaiacol with registering of optical density rise. Results fit completely with those of the classical Technicon autoanalyzer technique. The method is accurate, fast, easy to perform, and appliable to large series, while necessitating only 10 mul of serum.
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PMID:[Haptoglobin assay using the LKB 8600 reaction rate analyzer]. 119 May 74

The azlactone of p-nitrobenzoyl-valine (Nbz-Val) has been used for modification of xi-amino groups of lysine in haptoglobin type 1-1, in hemoglobin, and in the haptoglobin-hemoglobin complex. By the use of this reagent 95% of amino groups in haptoglobin and 90% in hemoglobin have been blocked without any changes in peroxidase activity of the formed complexes: Nbz-Val.haptoglobin with hemoglobin, Nbz-Val. hemoglobin with haptoglobin, and Nbz-Val.(haptoglonin-hemoglobin). After reduction and reoxidation, Nbz-Val.haptoglobin was found to retain 90% of peroxidase activity when complexed with hemoglobin. Beta chains separated either from haptoglobin or Nbz-Val.haptoglobin showed 15% of peroxidase activity in the complex with hemoglobin, alpha chains of the same origin were completely inactive. Whereas recombination of haptoglobin from alpha and beta chains resulted in 42% hemoglobin-binding capacity, renaturation of Nbz-Val.haptoglobin from separated subunits was found to proceed with almost 100% yield. In immunodiffusion with rabbit anti-haptoglobin or anti-Nbz-Val.haptoglobin sera, preparations of haptoglobin and Nbz-Val.haptoglobin after reduction and reoxidation or after recombination from separated subunits gave similar precipitation arcs showing the reaction of immunological identity.
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PMID:Effect of modification on physicochemical and biological properties of haptoglobin. VI. Reaction with azlactone of p-nitrobenzoyl-valine. 119 81

The shifts which occur in the ultraviolet spectra of haptoglobin 1-1 (Hp) and a conformational isomer with lower affinity for hemoglobin (Hp), in response to temperature and solvent changes, have been measured by difference spectra. The thermal difference spectra provide evidence for a different participation of tryptophyl residues in the conformational stability of Hp and Hp. Solvent perturbations have allowed an estimation to be made of the number of surface chromophores in the native Hp and Hp. These results are compatible with the existence of two Hp conformational isomers with different free energy, separated by a high-potential barrier.
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PMID:Thermal and solvent perturbation as probes of conformational heterogeneity of haptoglobin 1-1. 120 45

The following aspects of intravascular hemolysis are briefly reviewed: pathogenesis; binding of hemoglobin to haptoglobin, hemopexin or serum albumin; hemoglobin oxidation, dissociation and renal excretion. The dissociation constant of hemoglobin tetramer into dimers was determined by gel filtration at 37 degrees C, using normal plasma for elution. This constant (5.1 x 10(-6) mol/l was used for calculation of renal clearance of hemoglobin. The rate of hemoglobin autooxidation was measured in normal plasma applying varying partial oxygen pressures. The results confirm that the formation of methemoglobin is enhanced under hypoxic conditions.
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PMID:[The fate of hemoglobin in the plasma]. 120 20

The peroxidatic activity of hemoglobin (Hb) is known to be enhanced when this hemoprotein is bound to haptoglobin (Hp). The peroxidatic reaction (H2O2, guaiacol as donor) has been kinetically studied (Steady-state) in the presence of free or rabbit-haptoglobin bound human hemoglobin and some of its derivatives, all in ferricyano-form. With free Hb+ CN, we observed linearity of Lineweaver and Burk plots in a wide range of concentrations, the donor's behaviour was therefore assumed to obey the Michaelis-Menten mechanism. When Hp-Hb+ CN is the enzyme, the donor's behaviour is more complicated, analysis shows the existence of two kinds of donor's binding sites. The possibility whether this behaviour might correspond to the intrinsic properties of Hb chains, as revealed after combination with Hp, was examined. The peroxidatic activity of free and Hp-bound alpha and beta chains of Hb were studied. The alpha chains of Hb combine with Hp whereas the beta chains fail to do so. In order to make useful comparisons, the peroxidatic activity of Hp-bound alpha and beta chains were studied by the use of Hp-semihemoglobin complexes where the semihemoglobins carried heme on only one type of chain (alpha or beta). Results did not show an evident correlation between the activities of the two free or bound types of chains and those of the two classes of binding sites revealed in Hp-Hb+ CN. Moreover, it appeared that the heme-free complementary chain might influence the activity of the heme-carrying alpha or beta chain in semihemoglobins and Hp-semihemoglobin complexes. The binding or protoporphyrin on free and Hp-bound semihemoglobins leads to species which exhibit structures close to that of Hb and Hp-Hb complex respectivley. Results of studies on these derivatives brought up new interesting data : when the porphyrin ring alone is bound to the heme deficient chains (alpha or beta), in Hp-semihemoglobin complexes, the same peculiar behaviour, already observed with Hp-Hb complex, is found again. The structural implications of these results are discussed.
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PMID:Studies on free or haptoglobin-bound hemoglobin and derivatives (semihemoglobins and porphyrinated semihemoglobins). Some aspects of their peroxidatic activity. 122 41

A simple and rapid method is described for the determination of serum hemoglobin. Free hemoglobin shows no peroxidase activity but human hemoglobin-human haptoglobin complex presents a peroxidase activity which permits hemoglobin determination. It is shown that a good source of haptoglobin is constituted by pools of non-hemolyzed human serums.
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PMID:[Micro-determination of hemoglobin by measuring the peroxidase activity]. 122 21


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