Physicochemical properties of bile acids and their relationship to biological properties: an overview of the problem
Year: 1984
Type: article
Abstract: The structure of the bile acid molecule is described and correlated with physiochemical properties of bile acids such as solubility, ionization, and micelle formation. Recent measurements of the critical micellar concentration (CMC) of a large number of bile acids indicate that the CMC is influenced by both side chain and nuclear structure. Bile acids with hydroxy substituents on both sides of the steroid nucleus are non-amphipathic and do not form micelles, and decreasing the length of the side chain causes an exponential increase in the CMC. Bile acid ionization, measured by titration in alcohol-water mixtures, is shown to be uninfluenced by nuclear substituents; the pKa of all unconjugated bile acids is about 5. Interactions of bile acid solutions with Ca2+ are discussed; recent work indicates that cholyl conjugates bind Ca2+ as monomers in solution. Model systems relevant to biological processes are classified, as are some of the physicochemical parameters of these systems. Biological processes involving bile acids are tabulated, and corresponding model systems are assigned to each. Some biological processes such as bile acid transport show marked species differences, suggesting that physicochemical parameters are insufficient to explain biological differences. It is recommended that the physical chemist study a variety of bile acids, that the biologist study a variety of species, and that both collaborate to attempt to factor out the extent to which physicochemical properties of bile acids can explain their biological properties.
Source: Journal of Lipid Research
Authors: A F Hofmann, A Roda
Institutions: University of California San Diego, University of Bologna
Language: English
Subfield: Physical and Theoretical Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,430
OpenAlex ID: W2171070582