Department of Biology, New York University, New York.
Biochim Biophys Acta 1178: 87-96 (1993)
Abstract
Arachidonic acid has recently gained attention as a result of current
evidence indicating that it may play the role of a 'second messenger' in
signal transduction processes. In order to gain insight into the
mechanism behind its action, quenched molecular dynamics simulations
were performed on arachidonic (20:4) and related fatty acids: linoleic
(18:2), oleic (18:1), arachidic (20:0), and stearic (18:0). The
angle-iron structure, representative of arachidonic acid in the crystal
or very-low-temperature state, readily gave way at higher temperature to
a dominant hairpin structure whereby the COOH end of arachidonic acid
comes into close proximity with the C14-15 pi-bond resulting in a packed
pi-bond-rich loop. The lowest energy conformer for arachidonic acid was
found to be 10.65 kcal/mol below that of the energy-minimized crystal
structure. In the case of saturated fatty acids, the crystal all-trans
conformation remained the lowest energy form. Analysis of conformational
energy contours for carbon-carbon torsion angles representative of
fatty acids suggest that the flexibility of arachidonic acid is, in
part, a result of the relative torsional freedom of C-C (single) bonds
located between or adjacent to C = C (double) bonds. It is hypothesized
that the ability of arachidonic acid to form packed structures with
curved regions containing pi-bonds may allow for hydrophobic
interactions with proteins, and/or hydrogen bonding between the pi-bonds
of arachidonic acid and polar groups of the protein structures.
Mesh Headings
Unique Identifier: 93320126
Chemical Identifiers (Names)