To explore the effects of mimosine in the conformational preferences of short peptides we have run MD simulations of two model systems, with sequences Ace-XGPGXG-Nme and Ace-XGPGXGGX-Nme (see Figure ). In these systems, X can be either the mimosine amino acid (Mms), Phe or Tyr, which we use for the purpose of comparison. Peptide chains were initially modelled as right handed a-helices using the Molefacture plugin of VMD. They were placed in periodic orthorhombic boxes leaving 1 nm of margin in each direction. The systems were minimized using the steepest descent algorithm and then equilibrated in two stages. First, we run a 100 ps simulation in the NVT ensemble and then another 100 ps in the NPT ensemble, both at 300 K. Simulations were run using the velocity-rescaling thermostat and the Parrinello-Rahman pressure coupling to fix the pressure at 1 bar. Production MD simulations were run using the same conditions as the NPT equilibration. Dynamics were propagated for 500 ns and 3 replicas were run for each system using a 2 fs time step. Electrostatic interactions were calculated using PME and the cutoffs for both electrostatic and van der Waals interactions were 1 nm. All the MD simulations were performed using the ff99SB and ff03 force fields (including the mimosine amino acid) and the TIP3P water model using the Gromacs package (version 2018).