The propensities of amino acids to form parallel beta-sheets

This paper reports synthetic and structural studies of a 16-membered combinatorial library of chemical models for parallel beta-sheets (1) and two four-membered libraries of controls (2 and 3). The libraries contain glycine, alanine, valine, and leucine residues, and the structural studies use H-1 NMR and IR spectroscopy to measure the relative degrees of intramolecular hydrogen bonding of the parallel beta-sheet models in chloroform solution. These studies indicate that leucine and valine are relatively good at forming parallel beta-sheets, alanine is moderate, and glycine is poor (L, V > A > G).