alanyl-alanyl-alanine and alanyl-alanyl-alanyl-alanine

Poly-l-alanine (PLA) sequences are key elements of the crystalline domains of spider dragline and wild silkworm silks. In the present work,

Topics: Crystallization; Nuclear Magnetic Resonance, Biomolecular; Oligopeptides; Protein Conformation, beta-Strand; Protein Structure, Quaternary; Proton Magnetic Resonance Spectroscopy

Alanine oligopeptides provide a key structure of the crystalline domains of the silks from spiders and wild silkworm and also the sequences included in proteins such as antifreeze proteins and amyloids. In this paper, the local dynamics of alanine oligopeptides, (Ala)

Topics: Carbon-13 Magnetic Resonance Spectroscopy; Hydrogen Bonding; Molecular Dynamics Simulation; Oligopeptides; Protein Conformation, beta-Strand; Water

The di-, tri-, and tetrapeptides of L-alanine have been studied in aqueous solution by 13C n.m.r. spectroscopy at 25 and 50 MHz. By using selectively 13C enriched analogs containing either 90% 13C methyl or carbonyl carbons and measurements as a function of pH, assignment of the chemical shifts of the peptides has been made. T1 and NOE measurements of the peptides in their cationic, anionic, and zwitterionic states have been recorded as a function of concentration. The results show considerable segmental motion along the backbone carbons of the peptides, with only small changes occurring in the dynamic motions of the peptides as their charge states are altered. The lack of concentration dependence of the chemical shift and T1 values, as well as the similarity of T1 values for individual peptides in the three charge states, indicate that the peptides do not self-associate in aqueous solution.

Topics: Alanine; Dipeptides; Hydrogen-Ion Concentration; Magnetic Resonance Spectroscopy; Oligopeptides; Protein Conformation; Structure-Activity Relationship