Abstract:
:Human erythrocyte spectrin prepared from fresh blood is a mixture of different association states. Depending on the manner of preparation, the two-chain dimer or the tetramer predominates. These forms are not in rapid thermodynamic equilibrium. The molecular weight of the dimer by sedimentation and diffusion and by light scattering is about 5 X 10(5). The frictional properties indicate a low or moderate asymmetry (axial ratio in the range 2-10), and from the angular dependence of light scattering intensity an upper limit of about 80 A can be set for the radius of gyration. The tetramer similarly has a moderate asymmetry. Electron microscopy reveals that the dimer is a compact, slightly elongated molecule, and that the tetramer probably consists of two parallel dimers. On increasing the concentration of solutions containing spectrin dimers, oligomers are formed, which are not rapidly dissociated on dilution. At very low protein concentrations (below about 0.05 mg/mL) there is evidence of the onset of a rapid dissociation equilibrium between dimers and single chains. Other physical properties of the spectrin have been measured. The size and shape of the spectrin molecule would seem to rule out any major physical resemblance to myosin.
journal_name
Biochemistryjournal_title
Biochemistryauthors
Kam Z,Josephs R,Eisenberg H,Gratzer WBdoi
10.1021/bi00644a028subject
Has Abstractpub_date
1977-12-13 00:00:00pages
5568-72issue
25eissn
0006-2960issn
1520-4995journal_volume
16pub_type
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