SIZE AND ASYMMETRY OF SPATIAL DISTRIBUTIONS FOR UNPERTURBED TRIGLYCERIDES

A triglyceride in the interior of a chylomicron or very low density lipoprotein is essentially unperturbed by long-range interactions. Configuration-dependent properties for unperturbed triglycerides are obtained from a representative sample generated by Monte Carlo methods. Necessary a priori and conditional probabilities were obtained from a rotational isomeric state treatment which incorporates first-and second-order interaction. Triglycerides studied have 1-22 carbon atoms in each acyl group. Unperturbed radii of gyration, (s2)01/2, are in the range 8-10 Å for those triglycerides which occur most frequently in human chylomicrons and very low density lipoproteins. Asymmetry of the spatial distribution was assessed by examination of averaged principal moments ((L12)0 ≥ (L22)0 ≥ (L32)) of the moment of inertia tensor. An increase in asymmetry occurs upon progressing from triformin to tricaprylin, due almost entirely to a decrease in L22)0/L12)0. The higher triglycerides examined all have essentially identical asymmetries, L22)0/L12)0 ≈ L32)0/L12)0 ≈ 1/12-Thus the increase in average dimensions as the acyl group goes from C8 to C22 is achieved with no alteration in the asymmetry of the spatial distribution. Introduction of unsaturation. as it occurs in oleic and linoleic acids, brings about a reduction in (s2)01/2, but does no* significantly alter the asymmetry. © 1979, American Chemical Society. All rights reserved.