Collagen translational diffusion coefficient

Figure 4.6. Normalized autocorrelation function. Autocorrelation function for collagen single molecules. The autocorrelation function G(nAt) is normalized by dividing all points by the first experimental point G(l). The autocorrelation function decays to a value of the average squared intensity of scattered light divided by G(l). The average squared intensity is proportional to the weight average molecular weight, whereas the rate of decay is related to the translational diffusion coefficient. Reproduced from Silver, 1987.

Figure 4.7. Determination of translational diffusion coefficient. Plots of ln[(G(nAf))/B) - 1] versus time for collagen a chains (top) and mixtures of a chains and P components (bottom). The translational diffusion coefficient is obtained by dividing the slope of each line by -2Q2, where Q is the scattering vector. B is the baseline of the autocorrelation function. Note for single molecular species, the slope is constant, and for mixtures with different molecular weights, the slope varies (molecular weight for a chains is 95,000 and for y components is 285,000). (reproduced from Silver, 1987).

A measurement of physical parameters in solution for isolated macromolecules provides a manner by which the shape of a macromolecule can be determined. The approximate dimensions and axial ratio or radius can be calculated by applying Equations (4.3) through (4.17). As shown in Figure 4.10, the particle scattering factor for collagen molecules depicted in Figure 4.9 is more sensitive to bends than is the translational diffusion coefficient. 

Figure 5.5. Measurement of physical properties during initiation of collagen self-assembly. Translation diffusion coefficient (D20-w) (top) and intensity of scattered light at 90° (bottom) versus time for type I collagen. Note translational diffusion constant decreases, whereas intensity of scattered light remains initially unchanged.

Fletcher, G.C. (1976) Dynamic light scattering from collagen solutions. I. Translational diffusion coefficient and aggreation effects. Biopolymers, 15, 2201-2217. 

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