Binding of cholesterol

We also investigated chelate binding by dimers of a synthetic hydrophobic macrocycle, in place ofthecyclodextrins [187]. In the systems examined the chelate effect was weaker than that seen with the cyclodextrin dimers. We also studied the strong binding of cholesterol by some cyclodextrin dimers and a cyclodextrin polymer, and saw that the large sterol could occupy parts of two binding cavities [188]. 

In the next step, the cholesteryl ester entities copolymerized in the shell, were split by carbonate ester hydrolysis. The hydrolysis was carried out in sodium hydroxide in methanol. Thereby, an analogue of cholesterol, the target molecule for later recognition, was removed from the copolymer network. The particles were now ready for non-covalent binding of cholesterol. To quantify the binding behavior of colloidal MIPs, they were mixed with a cholesterol containing solution, separated from the liquid and the cholesterol concentration in the supernatant was quantified by HPLC. 

Fig. 5. Stoicliiometric relationship between cholesterol mass transfer and SCP2. In A and B, the effect of SCP2 on net cholesterol mass released from adrenal lipid droplets and binding of cholesterol to SCP2 in the droplet-free subnatant is shown. The small amount of cholesterol transfer which occurred in the absence of SCP2 has been subtracted. In C and D, the effect of SCP2 on the depletion of cholesterol from the lipid droplets and the accumulation of cholesterol mass in aminoglutethimide-treated mitochondria is shown. Experimental details are described in ref. 33.

As noted above, MeC trimerizes and MeLC does not self-associate in CHCI3. Under these conditions, Foster et al. [202] used vapor pressure osmometry to show that solubilized cholesterol (which dimerizes in CHCI3 [203]) heteroassociated with MeC but not with MeLC. The result was a 1 1 mixed dimer complex of cholesterol and MeC with a molar free energy of formation which was 33% that for the trimerization of MeC in the same solvent [202]. The bonding is presumably via the 3-hydroxyl functions in both steroids this interaction may be of potential importance in the binding of cholesterol to bile acids and salts within membranes and mixed micelles. 

The results showed the immobilization to cause an increase in the specific catalytic activity of MnAdTAPhP. This effect might be due to the additional binding of cholesterol molecules by hydrophobic fragments of the macromolecule chain resulting... 

Figure 8 (a) Binding of cholesterol to cholesterol-imprinted and control polymers, from a 2 mM solution of cholesterol in hexane, as a function of polymer concentration, (b) Binding of cholesterol and various cholesterol analogues (2 mM) to the cholesterol-imprinted polymer, prepared by the sacrificial spacer method. Reprinted with permission from Journal of the American Chemical Society. Copyright 1995 American Chemical Society (Ref. 10). 

Sreenivasan also made qualitative investigations into the extent of hydrogen bonding associated with the template-monomer binding. Carbonyl infrared absorption shifts were measured in the absence and presence of cholesterol. There is a 15 cm shift upon cholesterol binding to acrylic acid [1721-1706 cm ], whereas a more pronounced 26 cm shift is observed for the binding of cholesterol to copper acrylate [1729-1703 cm ]. The larger shift is attributed to an enhanced interaction in the Cu acrylate-cholesterol system. 

Beel AJ, Sakakura M, Barrett PJ, Sanders CR. Direct binding of cholesterol to the amyloid precursor protein an important interaction in Upid-Alzheimer s disease relationships Biochim Biophys Acta. 2010 1801(8) 975-982. Barrett PJ, Song Y, Van Horn WD, et al. The amyloid precursor protein has a flexible transmembrane domain and binds cholesterol. Science. 2012 336(6085) 1168-1171. 

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