Chain length biomembranes

In the last decade, many efforts have been devoted to the study of the influence of chiral molecules on the enzymatic processes at the membrane surfaces. V -Acyl-L-and D-amino acid derivatives have been employed as model substances for simulating biomembranes and interfacial processes at biomembrane surfaces [32]. It has been found that chiral monolayers of V -acylamino acid methyl esters on a pure water surface showed that hydrogen bond formation via NH, COOH, and p-hydroxyphenyl groups (i.e., tyrosine side chains) lead to a pronounced chiral discrimination [33,34]. Homochiral (d-d or L-L interactions) and heterochiral (d-l interaction) discrimination can be observed depending on the area per molecule ( min)> which depends on the conformation of the amino acid residue and on the alkyl chain length. 

The phase transition of lipid bilayers which comprise phospholipid mixtures, or phospholipids with different lengths of acyl chains, are of great importance due to their similarities with biomembranes or with lipid drug carriers such as liposomes, it is important to study the phase transitions and to detennine the exact crystalline mesophases of the mixed system. Thermal analysis studies indicated that the mi.xed lipids provide higher melting temperatures compared to those of pure lipids. This phenomenon occurrs w hen the lengths of the acyl chains are substantially different. 

Sugar residues, belonging to glycoproteins or glycolipids, are also present at the outer surfaces of cell membranes, as well as cholesterol and vitamin E. Biomembranes usually contain carbon chains of differing lengths, moreover opposite surfaces have somewhat different compositions and bio layers are asymmetric. (Biomembranes do not in reality correspond to the idealised representations which are often nsed e.g. Figures 11.6 and 11.7.)... 

---