The -BF-NH- link as a peptide-bond surrogate.
A new peptidomimetic is proposed, resulting from substitution of the C═O carbonyl group by a B-F bond at the amide linkage. The effects of such chemical alteration are theoretically investigated through comparative calculations on dimethyl-fluoro-aminoborane H(3)C-BF-NH-CH(3) and N-methylacetamide H(3)C-CO-NH-CH(3), the simplest model of a peptide linkage. While little difference is found regarding size, electronic structure, and plaque rigidity, substantial distinctions are, however, observed between the polarities and association energies of the two compounds, with a B-F···H-N hydrogen bond estimated to be about one-third as strong as the natural C═O···H-N one. The conformational maps of the corresponding dipeptide models exhibit similarities and distinctions, which partly account for helical oligomer properties. Although capable of a high level of organization, the chains made of fluoro-aminoborane units show overall less structuration and more plasticity than their peptidic counterparts. Contrasts with fluorine-containing peptidomimetic 2-fluoro-2-butene are further underlined.
Laboratoire de Chimie et Physique Quantiques (CNRS, UMR-5626), IRSAMC, Université Paul-Sabatier, 31062 Toulouse Cedex, France.
Simon
S
Mathieu
Georges
G
Trinquier
D000081:Acetamides / Q000737:chemistry; D001880:Boranes / Q000737:chemistry*; D006860:Hydrogen Bonding; D007536:Isomerism; D010455:Peptides / Q000737:chemistry* / Q000378:metabolism; D013816:Thermodynamics
D000081:Acetamides; D001880:Boranes; D010455:Peptides; C018595:N-methylacetamide