The Structure of the Protonated Serine Octamer

Area of Science:

• * Physical Chemistry
• * Computational Chemistry
• * Biophysics

Background:

• * Protonated serine clusters, particularly the eight-unit cluster (Ser8H+), exhibit unique properties like high abundance in mass spectra and homochirality.
• * Previous experimental and theoretical studies have not reached a consensus on the definitive structure of Ser8H+.

Purpose of the Study:

• * To determine the three-dimensional structure of the protonated serine eight cluster (Ser8H+).
• * To elucidate the structural basis for the observed homochiral preference and facile replacement of serine units in the cluster.

Main Methods:

• * Combination of infrared spectroscopy for experimental data acquisition.
• * Ab initio molecular dynamics simulations for theoretical structure determination and stability analysis.

Main Results:

• * A novel, stable three-dimensional structure for Ser8H+ was determined.
• * The new structure is significantly more stable (∼25 kcal mol^-1) than previously reported structures.
• * The determined structure successfully explains the observed homochiral preference and the facile replacement of two serine units.

Conclusions:

• * The presented structure provides a consistent explanation for key experimental observations of Ser8H+.
• * This work resolves long-standing ambiguities regarding the structure of this important amino acid cluster.