Environmental Engineering Reference
In-Depth Information
NaCl concentration; we have also included snapshots of the spatial configuration
of the protein at certain salt concentration where the folding changes intermittently
from loops (or “closed” conformations) to an extended (or “open”) conformation.
At the top part of Fig. 1 we include snapshots of the open conformations and in the
bottom part the close conformations. The arrows at the top of Fig. 1 indicate the 0.5,
0.9, 1.1, 1.4 and 1.8M concentrations, where the open conformations take place.
The arrows shown at the bottom of Fig. 1 represent the concentrations 0.6, 1.0,
1.7 and 2.0M, which correspond to close conformations. A behavior qualitatively
similar to this has been obtained by Alarcón and coworkers (Alarcón et al. 2013 )on
biopolymers, by Hsiao (Hsiao and Luijten ( 2006 )) for polyelectrolytes of multivalent
ions, and in experiments (Kozer et al. 2007 ;Dawsonetal. 1997 ; Käs et al. 1996 ). The
formation of closed configurations is the result of the electrostatic charge inversion
mechanism (Nguyen et al. 2000 ), while the open configurations are attributed to elec-
trostatic repulsion between adjacent monomers (Wong and Pollack 2010 ). Trapping
of cholesterol and other fatty acids becomes favorable when closed configurations
are formed because these molecules are closer to APOA1, therefore the formation of
hydrogen bonds between them is promoted. Under these circumstances this protein
would have an increased functionality. To test the stability of the open and close
configurations seen in Fig. 1 , we have monitored their evolution in time, which we
show in Fig. 2 . The curves seen on the top of the figure correspond to open structures,
while those at the bottom correspond to closed conformations.
Fig. 2 Time evolution of the radius of gyration ( R g ) of APOA1 at various NaCl concentrations, as
specified in the inset on the right border of the figure. The top curves correspond to the so-called
open structures; those at the bottom correspond to closed configurations
Search WWH ::




Custom Search