The Molecular Properties of the Methaemoglobin of <i>Chironomus plumosus</i> L. in Solution

Behlke, Joachim; Scheler, W

doi:10.1111/j.1432-1033.1967.tb19510.x

Cited by 19 publications

(8 citation statements)

References 8 publications

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“…In C plumosus and C th ummi, both monomeric (mol wt '" 16,(00 ) and dimeric forms of hemoglobin occur (Table 2), dissociation being favored at elevated pH, although the situation in vivo is not certain (339,341,(378)(379)(380). In C tentans and some other species, however, only the monomers are fo und ( Table 2; 93).…”

Section: Hemoglobinsmentioning

confidence: 99%

Insect Plasma Proteins

Wyatt¹,

Pan²

1978

Annu. Rev. Biochem.

287

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Section: Hemoglobinsmentioning

confidence: 99%

Insect Plasma Proteins

Wyatt¹,

Pan²

1978

Annu. Rev. Biochem.

287

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“…Furthermore, pHdependent association-dissociation equilibria have been observed with Chirononaus plumosus haemoglobins not separated chromatographically [15,3]. The Bohr effect and the shape of the 0,-binding curves might be related to these equilibria of aggregation.…”

Section: Resultsmentioning

confidence: 99%

Heterotropic Allosterism of Monomeric Haemoglobins of Chironomus thummi thummi

et al. 1972

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Two monomeric haemoglobins of the insect Chironomus thummi thummi are described which, though their 0,-binding curves are exactly hyperbolic (Hill coefficient n = 1.00), do exhibit a Bohr effect (haemoglobin 111, 0.28 at 25 "C; haemoglobin IV, 0.42 at 25 "C). Thus, these haemoglobins can exist in two conformational states differing in 0,-affinity. The states are characterized also by different A S values ; the acid conformation with low affinity possessing a low, the alkaline conformation with high affinity a higher A X value.I n this paper the Bohr effect is regarded from generalizing aspects, i. e. as an interaction between the proton-binding site and the 6th coordination point of the iron which can therefore be studied as well with oxidised haemoglobin. I n the case of the oxidised form of haemoglobin the allosteric interaction between the proton-binding site and the coordinated H,O was the basis of our experiments.Absorbance and ellipticity of the oxidised form of haemoglobin measured at different wavelengths as a function of pH result in titration curves differing in the position of their inflection points. On the basis of the circuit process described previously [21], the percentage distribution of the constituent conformation isomers according to pH and the allosteric pK values (pKa:! = 7.30; pKal = 7.00) were calculated.In electron spin resonance spectroscopy the heterotropic allosterism is revealed by a change in the symmetry of the intramolecular electric field of the H,O-derivative. The acid conformation with rhombic symmetry ( g i l # 912) is transformed into the alkaline conformation with axial symmetry. The acid conformation is further characterized by five hyperfine structure lines in the gill signal, showing the d-electrons to interact with two N-nuclei in the z-direction. The hyperfine structure lacking in the alkaline conformation indicates a larger distance of the proximal imidazole from the iron. The pH-dependent variation of this distance controlls the affinity of the sixth ligand.A possible molecular mechanism of the Bohr effect of haemoglobin I11 is described, considering the interactions, revealed by the atomic model [8].It is shown that the Bohr effect mechanism in Chironomus haemoglobin is based on the same conditions of tertiary structure as in the case of vertebrate haemoglobins [ 7 ] . These conditions of tertiary structure, however, are realized with completely differing primary structures.The oxygen-binding properties of isolated haemoglobins of Chironomus has recently been described by several authors [l -31. Chromatographically isolated haemoglobins of Chironomus thummi thummi were shown by Sick and Gersonde [l] to possess hyperbolic 0,-binding curves and more or less strong Bohr effects. Formanek and Amit [2], however, failed to find a Bohr effect for haemoglobin 111, the individual haemoglobin characterized by sequence [4] and X-ray structure analysis [ 5 ] . Lampe and coworkers [3] have found Hill coefficients up to n = 2 a t pH 9 for haemoglobins of Chironomus plumosus, und...

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“…Durch Begasen mit CO wurde HbCO erhalten. Sedimentationsuntersuchungen t?ihrten wir mit einer analytischen Ultrazentrifuge G 110, MOM Budapest, durch [4] . Die Sedimentationskoeffizienten, North-Holland Publishing Company --Amsterdam k. w, wurden in AbhQgigkeit von der Proteinkonzen'tration bzw.…”

Section: Methodsunclassified

Dder einfluss von liganden auf den assoziationsgrad des desoxy‐hämoglobins der flussneunaugen (lampetra fluviatilis L.)

Behlke

Scheler

1970

FEBS Letters

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In alkaline aqueous solution, the sedimentation coefficients of DeoxyHb, HbO2 and HbCO of Lampetra fluviatilis L. are 1.9 f 0.1 S. This value corresponds to a molecular weight of about 17,000, i.e. the value of a single haem polypeptide chain. In weak acidic conditions, both the non-liganded DeoxyHb and the liganded forms, HbO2 and HbCO, associate to form dimers and oligomers. The monomer-oligomer transitions of these compounds take place at different pH values: DeoxyHb pHO.5 ?. 6.7; HbO2 and HbCO pHO.5 %I 5.9. With respect to the association modus, the equilibrium: 4 Hb * 2 Hb2-b4 may be preferred.

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The Molecular Properties of the Methaemoglobin of Chironomus plumosus L. in Solution

Cited by 19 publications

References 8 publications

Insect Plasma Proteins

Insect Plasma Proteins

Heterotropic Allosterism of Monomeric Haemoglobins of Chironomus thummi thummi

Dder einfluss von liganden auf den assoziationsgrad des desoxy‐hämoglobins der flussneunaugen (lampetra fluviatilis L.)

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