Decker, H. and Hartmann, H. and Sterner, Reinhard and Schwarz, E. and Pilz, I. (1996) Small-angle X-ray scattering reveals differences between the quaternary structures of oxygenated and deoxygenated tarantula hemocyanin. FEBS letters 393 (2-3), pp. 226-30.
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Small-angle X-ray scattering (SAXS) curves have been recorded for the oxygenated and deoxygenated states of the 4 x 6-meric hemocyanin from the tarantula Eurypelma californicum. A comparison of the curves shows that the quaternary structures of the two states are different by three criteria, which all indicate that the hemocyanin is less compact in the oxygenated compared to the deoxygenated form: (a) The radius of gyration is 8.65 +/- 0.05 nm for the deoxy- and 8.80 +/- 0.05 nm for the oxy-form. (b) The maximum particle dimension amounts to 25.0 +/- 0.5 nm for the deoxy- and to 27.0 +/- 0.5 nm for the oxy-form. (c) A dip in the intramolecular distance distribution function p(r) is more pronounced and shifted to larger distances in the oxy-form. The p(r) functions based on SAXS measurements were compared to p(r) functions deduced from published electron microscopical images of three different 4 x 6-meric hemocyanins from closely related species. The p(r) functions of SAXS and electron microscopy were similar in one case, whereas in the other two cases the distance between the two 12-meric half-molecules had to be changed by 1-1.5 nm to obtain good agreement. The differences between the p(r) functions of oxygenated and deoxygenated 4 x 6-meric tarantula hemocyanin are much larger than one would expect from a comparison of X-ray structures of the oxygenated and deoxygenated states of a closely related 6-meric hemocyanin. Thus, the conformational changes upon oxygenation occur at various levels of the quaternary structure, as postulated by hierarchical theories of allosteric interactions.
|Institutions:||Biology, Preclinical Medicine > Institut für Biophysik und physikalische Biochemie > Prof. Dr. Reinhard Sterner|
|Subjects:||500 Science > 570 Life sciences|
|Refereed:||Yes, this version has been refereed|
|Created at the University of Regensburg:||Yes|
|Deposited On:||22 Mar 2010 09:28|
|Last Modified:||22 Mar 2010 09:28|