1.D.153.  The Hetero-Oligomeric Peptidic Synthetic 3-in-1 Transporter (HOP-3in1T) Family

A  crystal  packing-inspired  social  self-sorting  strategy  broadly  applicable  to diverse types of H-bonded peptidic frameworks has been designed (Zeng et al. 2021). Specifically, a  crystal  structure  of  H-bonded  alkyl  chain-appended monopeptides revealed an inter-chain separation distance of 4.8 Å dictated by the H-bonded amide groups, which is larger than the 4.2 Å separation distance desired by tightly packed
straight  alkyl  chains.  This  incompatibility  resulted  in  loosely packed alkyl chains, prompting an investigation of the feasibility of applying bulky tert-butyl groups, modified with an  anion-binding  group,  to  alternately  interpenetrate  the straight  alkyl  chains,  modified  with  a  crown  ether  group. Structurally, this social self-sorting approach generated highly stable hetero-oligomeric ensembles, having alternated anion- and cation-binding units vertically aligned to the same side. Functionally,  these  hetero-oligomeric  ensembles  promote transmembrane  transport  of  cations,  anions  and  more
interestingly, zwitterionic species such as amino acids (Zeng et al. 2021).

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