Structures of dipeptides: the head-to-tail story

Abstract

The hydrogen-bonding patterns in crystal structures of unprotected, zwitterionic dipeptides are dominated by head-to-tail chains involving the N-terminal amino groups and the C-terminal carboxylate groups. Patterns that include two concomitant chains, thus generating a hydrogen-bonded layer, are of special interest. A comprehensive survey shows that dipeptide structures can conveniently be divided into only four distinct patterns, differing by definition in the symmetry of the head-to-tail chains and amide hydrogen-bonding type, but also in other properties such as peptide conformation and the propensity to include solvent water or various organic guest molecules. Upon crystallization, the choice of pattern for a specific dipeptide is not random, but follows from the amino acid sequence.

Ferroelectric Properties and Phase Transition in Dipeptide Nanotubes

“…Structural studies that were conducted by Gorbitz [21][22][23] revealed that the FF-PNT has hexagon P 6 1 space group symmetry and this was later confirmed by other studies [26]. The X-ray analysis [13] showed that the temperature-driven process is changing the initial space hexagonal symmetry P 6 1 of hollow native FF-PNT to orthorhombic D 2 h of heat treated closed-end FF-PNF.…”

“…Such a classification allows observing diverse ferroelectric and related phenomena, which are described by tensors of the odd rank, such as piezoelectric, linear electro-optical, nonlinear optical effects, etc. Some of the dipeptide structures [21][22][23] considered by Gorbitz possess crystalline symmetries that related to pyroelectric classes, meaning a direct evidence of the existence of spontaneous electrical polarization. In this context, peptide molecular dipole engineering is intensively developed in the last years by Kimura [24].…”

“…First, conformation packaging problems of elementary building blocks-dipeptide molecules into tubular-like supramolecular structures has been thoroughly studied by Görb-itz [21][22][23]. He analyzed 160 dipeptides and showed that bioinspired peptide nanostructures, composed of peptide crystalline subunits, are structures without center of symmetry.…”

Unusual Absence of Head-to-Tail Chains in the Crystal Structure of Glycyl-l-glutamyl-l-phosphoseryl-l-leucine

“…The phosphate moiety in phosphoseryl residue 1 acts as a single proton donor (O10-H10ÁÁÁO1W), but six times as a proton acceptor, while the corresponding group in phosphoseryl residue 2 is a proton acceptor five times and a donor once (O20-H20AÁÁÁO3W/O3A), if the disorder of O3W/O3A is considered. It should be noted that no head-to-tail chains, which are characteristic in common peptide aggregation [3,4], can be found in the aggregation of glycyl-L-glutamyl-L-phosphoseryl-L-leucine. Instead the hydrogen bonds connect the N-terminal amino group to the phosphate groups of the peptide.…”

Bioferroelectricity and biopiezelectricity

“…For the first time, the analysis of the supermolecu lar PT structure formed from different peptides was performed in [16][17][18] (a total of 160 different peptides were analyzed). It was shown that an overwhelming majority of considered structures consist of separate crystalline substructures without a center of inversion.…”