Isolation, characterization and oxygen equilibrium of an extracellular haemoglobin from Eunice aphroditois (Pallas)
| Autor: | J V Bannister, W H Bannister, A Anastasi, E J Wood |
|---|---|
| Rok vydání: | 1976 |
| Předmět: |
Circular dichroism
Analytical chemistry Bohr effect Biochemistry Dissociation (chemistry) Hemoglobins Spectrophotometry medicine Animals Magnesium Amino Acids Molecular Biology Gel electrophoresis Chromatography Molecular mass medicine.diagnostic_test Chemistry Circular Dichroism Spectrophotometry Atomic Polychaeta Cell Biology Hydrogen-Ion Concentration Molecular Weight Microscopy Electron Isoelectric point Oxyhemoglobins Sedimentation equilibrium Ultracentrifugation Research Article |
| Zdroj: | Biochemical Journal. 159:35-42 |
| ISSN: | 0264-6021 |
| Popis: | The extracellular haemoglobin from the polychaeta,Eunice aphroditois, existed as a mixture of a heavy major component (so20, w = 56.96 +/- 0.125) and a light minor component (so20, w = 10.00 +/- 0.13S), the latter probably being a dissociation product of the former. The molecular weight of the purified heavier component, as detetermined by sedimentation equilibrium, was 3.44 X 10(6) +/- 0.04X10(6). The molecule had the electron-microscopic appearance typical of annelid haemoglobins, consisting of a stack of two hexagonal plates, with dimensions 26.32 +/- 0.27 nm across the flats of the hexagon, height of stack 17.86 +/- 0.34 nm. The sugar composition is reported, and the isoelectric point was approx. pH7.8. The haem content was 2.31 +/- 0.01%, corresponding to a minimal mol.wt. of 26700. Detergent/gel electrophoresis revealed the presence of at least four bands with molecular weights in the range 14600-31000. Five N-terminal amino acids were found. In addition to the 10S component, which co-existed with the 57S component at all pH values in the range 4.0-10.6, at low pH values (less than pH.5.0) A 16S and a 1.9 S component were found. The absorption and circular-dichroic spectra are reported, and the alpha-helical content, calculated from the ellipticity at 222 nm, was about 40%. The molecule bound O2 co-operatively with a maximum value of the Hill coefficient, h, of 3.9. Over the pH range 7.0-8.0 there was a positive Bohr effect. |
| Databáze: | OpenAIRE |
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