Effects of Cyclic vs. Acyclic Hydrophobic Subunits on the Chemical Structure and Biological Properties of Nylon-3 Co-Polymers.

Nylon-3 co-polymers containing both hydrophobic and cationic subunits can mimic the activity profile of host-defense peptides, if subunit identity and proportion are carefully selected. These sequence- and stereo-random co-polymers inhibit bacterial growth at relatively low concentrations, apparently via disruption of bacterial membranes, but they are relatively non-disruptive toward eukaryotic cell membranes (low hemolytic activity). In all previous examples, the hydrophobic subunits have contained cycloalkyl groups that incorporate the backbone Cα-Cβ bond. Here we have explored the effects of using analogous acyclic hydrophobic subunits. The results indicate that the replacing cyclic with acyclic hydrophobic subunits has a modest influence on biological properties. This influence appears to arise from differences in subunit flexibility.