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We experimentally demonstrated that paramylon, a storage polysaccharide of Euglena gracilis, is efficiently thermoplasticized by adding acyl groups that differ in alkyl chain length. Glass transition temperature of mixed paramylon esters was higher than those of plant-based polylactic acid (PLA), poly 11-aminoundecanoic acid (PA11), and petroleum-based acrylonitrile-butadiene-styrene (ABS) resin and was comparable to that of cellulose acetate stearate (CAS). Their thermoplasticity was equivalent to or higher than those of these reference plastics. The bending strength and bending elastic modulus of injection molded test specimens made from mixed paramylon esters were comparable to those of the reference plastics. While their impact strength was lower than that of specimens made from ABS resin and CAS, it was comparable to those of PLA and PA11. Euglenoid β-1,3-glucans are thus a potential component of thermoplastic materials.

The influence of channel and nonchannel forms of gramicidin A (c-gA and nc-gA, respectively) on the mixing behavior of phospholipids derived from 1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine (DMPE) and 1,2-distearoyl-sn-glycero-3-phosphoethanolamine (DSPE) has been examined in the physiologically relevant fluid phase by means of nearest-neighbor recognition methods (Davidson, S. K. M.; Regen, S. L. Chem. Rev. 1997, 97, 1269). Thus, when disulfide-based dimers were allowed to undergo monomer exchange at 60 °C in the presence of 5 mol % of nc-gA, the molar ratio of heterodimer to each homodimer was 1.55 ± 0.07; replacement of 50% of the exchangeable monomers with 1, 2-dipalmitoyl-sn-glycero-3-phosphocholine (a chemically inert diluent having an intermediate chain length and hydrophobicity) eliminated the ability of nc-gA to induce NNR. In sharp contrast, the presence of c-gA, at concentrations as high as 9 and 17 mol %, left the phospholipids in a randomly arranged state. The ability of gramicidin A to “communicate” its conformation to the surrounding phospholipids implies that lateral transmission of conformational information should also be possible between lipids and proteins in biological membranes.

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