Conformational states of the Rapana thomasiana hemocyanin and its substructures studied by dynamic light scattering and time-resolved fluorescence spectroscopy.
Hemocyanins are dioxygen-transporting proteins freely dissolved in the hemolymph of mollusks and arthropods. Dynamic light scattering and time-resolved fluorescence measurements show that the oxygenated and apo-forms of the Rapana thomasiana hemocyanin, its structural subunits RtH1 and RtH2, and those of the functional unit RtH2e, exist in different conformations. The oxygenated respiratory proteins are less compact and more asymmetric than the respective apo-forms. Different conformational states were also observed for the R. thomasiana hemocyanin in the absence and presence of an allosteric regulator. The results are in agreement with a molecular mechanism for cooperative dioxygen binding in molluscan hemocyanins including transfer of conformational changes from one functional unit to another.
Georgieva
Dessislava
D
Universitätsklinikum Hamburg-Eppendorf, Zentrum für Experimentelle Medizin, Institut für Biochemie und Molekularbiologie I, Hamburg, Germany.
Schwark
Daniel
D
Nikolov
Peter
P
Idakieva
Krassimira
K
Parvanova
Katja
K
Dierks
Karsten
K
Genov
Nicolay
N
Betzel
Christian
C
D000818:Animals; D003198:Computer Simulation; D006433:Hemocyanins / Q000032:analysis / Q000737:chemistry* / Q000648:ultrastructure*; D046529:Microscopy, Electron, Transmission; D008956:Models, Chemical; D008958:Models, Molecular; D008974:Mollusca / Q000378:metabolism*; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D012031:Refractometry / Q000379:methods*; D013050:Spectrometry, Fluorescence / Q000379:methods*
D006433:Hemocyanins