Critical concentration for

ATP-actin complex can polymerize, but the polymer once formed spontaneously depolymerizes. Depolymerization stops when the concentration of ADP-monomer in the medium reaches the value of the critical concentration for polymerization of ADP-actin (for review see Kom et al., 1987 Carrier, 1991). 

These free energies determine the critical concentrations for observing each peptide structure. In very dilute conditions, this class of peptides exist as random coil monomers in conformational flux. Above a critical concentration, C( pg, the concentration of monomer remains constant and formation of tapes occurs ... 

The measurement of the concentration dependence of the changes in surface potential was also used to find critical concentration for forming a micellar solution. Near this critical concentration, one can observe a very strong fall in A%. ... 

The concentration at which a steep rise in this curve begins has been termed as the critical or threshold concentration (2,3). Figure 6 shows such typical curves for PTF and BTF in n-hexane. Despite the fact that different shear rates are involved in capillary viscometry, it can be qualitatively said that at a given concentration, PTF viscosified n-hexane better than BTF. It is clear from Figure 6 that the critical concentration for these two compounds is above 0.7%, while analogous tri-n-alkyltin fluorides showed a critical concentration of less than 0.4% (3). This may be due to the presence of bulky Me3Si-groups nearer to the Sn-F bond, which causes some steric hindrance to auto-association. 

Actin comprises about 5-8% of the total protein of the neutrophil, and in resting cells about 50-70% of the actin pool exists as a monomer. This proportion of monomeric G-actin is far in excess of what would be predicted from the critical concentration for actin assembly in vitro. Thus, in vivo actin polymerisation and depolymerisation is regulated by the activities of a number of binding proteins, cations and other regulatory molecules, which are in turn regulated by the activation status of the cell. 

After elongation has proceeded for a sufficient period of time, the protomer and polymer will reach concentrations corresponding to the equilibrium constant Ko, which from our earlier discussion may be represented as k-/k+. This constant represents the critical concentration for polymer assembly, and protomer concentrations which fall below the magnitude of this constant will not spontaneously assemble. In this sec-... 

However, as discussed below critical concentrations for cellulose, in a variety of solvents, and based on optical observations under crossed polars are much lower than predicted using eauation 1 and kw = 2 q. Como et al. (4 point out one has to consider the possibili that the lattice model does not accuratelv predict the values of V2 and that V2 values using the Onsager (28) and Isihara (30) theories are about half that predicted by equation 1. 

Figure 1. Nucleation and growth of actin filaments. Nucleation is shown here as a thermodynamically unfavored process, which in the presence of sufficient actin-ATP will undergo initial elongation to form small filament structures that subsequently elongate with rate constants that do not depend on filament length. Elongation proceeds until the monomeric actin (or G-actin) concentration equals the critical concentration for actin assembly.

Corrin, M. L Klevens, H. B and Harkins, D. (1946). The determination of critical concentrations for the formation of soap micelles by the spectral behavior of pinacyanol chloride. J. Chem. Phys., 14,480-6. 

Under what conditions are colloids stable Explain qualitatively (with schematic diagrams) the forces between colloidal particles. How does the force of repulsion between them vary with concentration As the concentration of the colloid increases, there is the tendency to coagulate and in fact the critical concentration for coagulation gets less as the valence of the ions present increases (Schulze-Hardy rule). Give a detailed, although qualitative, rationalization of this law. (Bockris)... 

Van der Linden and Sagis (2001) have suggested that, once a critical concentration for gel formation is known, one can predict, for example, the dependence of the gel elasticity on the concentration of protein. The minimum gelation concentration may be expressed in terms of the basic fibre characteristics like the stiffness and also as a function of salt concentration (Veerman, 2004 Sagis et al., 2004). It is pointed out by van der Linden (2006) that there are two important factors which allow the manipulation of this minimum gelation concentration to an extremely low value. The first factor is that the nano-fibre should be robust against dilution. And the second is that the fibre should robust also with respect to other treatments, especially the adjustment of the pH. It would appear that each of these conditions is satisfied. 

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