The quaternary structure of Sepia officinalis haemocyanin
Wichertjes, T.; Gielens, C.; Schutter, W.G.; Préaux, G.; Lontie, R.; van Bruggen, E.F.J. (1986). The quaternary structure of Sepia officinalis haemocyanin. Biochim. Biophys. Acta 872(3): 183-194. https://dx.doi.org/10.1016/0167-4838(86)90270-0
In: Biochimica et Biophysica Acta. Elsevier: Amsterdam. ISSN 0006-3002; e-ISSN 1878-2434, more
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| Author keywords |
Haemocyanin; Quaternary structure; Immuno-electron microscopy; Electron microscopy; (S. officinalis) |
| Authors | | Top |
- Wichertjes, T.
- Gielens, C., more
- Schutter, W.G.
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- Préaux, G.
- Lontie, R.
- van Bruggen, E.F.J.
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| Abstract |
The haemocyanin (Hc) of Sepia officinalis is constituted of ten identical subunits (Mr about 390 000), which consist of eight functional (dioxygen-binding) units, designated by the letters a–h. A model is proposed for the quaternary structure of this HC, based on immuno-electron microscopy of whole molecules and on morphological studies of compact 1/5 molecules (consisting of two associated subunits). The immuno-electron microscopy was performed with IgG fractions containing antibodies specific for fragments abc, gh and de, respectively. Based on their general appearance, the immunocomplexes were divided into twelve types, whose occurernce was determined for the three IgG fractions. For each type of complex the location of the attachment sites of the IgGs was estimated in the cylindrical Hc molecule subdivided for this purpose into three regions (an upper, middle and lower third). The results indicate that functional units b to g form the wall of the cylindrical Hc molecule, while the two outer functional units of a and h are folded inside, thus forming a collar at the top and bottom of the cylinder. An experiment with a mixture of IgG fractions anti-abc and anti-gh showed that the ten subunits (a–h) lie parallel to each other, giving rise to an asymmetric molecule with, however, a symmetric appearance in the electron microscope. |
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