Protein oligomeric state

AFM images provide structural information on proteins and their interactions with other proteins or other molecules such asDNA. From visual inspection of the data, conformational properties of proteins can often be directly derived, as shown for example in Fig. 5a [9]. Quantitative statistical analyses allow for the extraction of further information on protein states and interactions. From the measured volume of particles in the images, their molecular mass can be calculated [10]. This calculation is based on an empirically derived linear relationship obtained with calibratirm proteins with a range of known molecular weights. From the molecular mass of the protein molecules and complexes, information can be derived on protein oligomeric states, protein-protein interactions, and complex stoichiometries. Single molecule resolution coupled with the analysis of statistical numbers of molecules or molecular assemblies supplies... 

Yeow, E. K. L. and Clayton, A. H. A. (2007). Enumeration of oligomerization states of membrane proteins in living cells by homo-FRET spectroscopy and microscopy Theory and application. Biophys. J. 92, 3098-104. 

These three examples emphasize the idea that a complete description of amyloid fibril polymorphisms will only be achieved when 3D structures at atomic detail become available (Luhrs et al., 2005). Last but not least, since the various morphologies observed for amyloid fibrils are defining the end point of the assembly process, an essential need is to properly define the early stages of fibril formation, namely the oligomeric states of the peptide or protein in solution prior to assembly into fibrils. 

The subsequent import mechanism has not been clarified, but it has a remarkable character it can pass proteins in a folded or even oligomerized state. 

Selected entries from Methods in Enzymology [vol, page(s)] Association constant determination, 259, 444-445 buoyant mass determination, 259, 432-433, 438, 441, 443, 444 cell handling, 259, 436-437 centerpiece selection, 259, 433-434, 436 centrifuge operation, 259, 437-438 concentration distribution, 259, 431 equilibration time, estimation, 259, 438-439 molecular weight calculation, 259, 431-432, 444 nonlinear least-squares analysis of primary data, 259, 449-451 oligomerization state of proteins [determination, 259, 439-441, 443 heterogeneous association, 259, 447-448 reversibility of association, 259, 445-447] optical systems, 259, 434-435 protein denaturants, 259, 439-440 retroviral protease, analysis, 241, 123-124 sample preparation, 259, 435-436 second virial coefficient [determination, 259, 443, 448-449 nonideality contribution, 259, 448-449] sensitivity, 259, 427 stoichiometry of reaction, determination, 259, 444-445 terms and symbols, 259, 429-431 thermodynamic parameter determination, 259, 427, 443-444, 449-451. 

Beck, K., Gambee, J. E., Kamawal, A., and Bachinger, H. P. (1997). A single amino acid can switch the oligomerization state of the a-helical coiled-coil domain of cartilage matrix protein. EMBOJ. 16, 3767-3777. 

Wagschal, K., Tripet, B., Lavigne, P., Mant, C., and Hodges, R. S. (1999). The role of position a in determining the stability and oligomerization state of a-helical coiled coils 20 amino acid stability coefficients in the hydrophobic core of proteins. 

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