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Characterizing a partially ordered miniprotein through folding molecular dynamics simulations: Comparison with the experimental data
Author(s) -
Baltzis Athanasios S.,
Glykos Nicholas M.
Publication year - 2016
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1002/pro.2850
Subject(s) - molecular dynamics , conformational isomerism , folding (dsp implementation) , chemistry , protein folding , crystallography , protein secondary structure , helix (gastropod) , chemical physics , computational chemistry , chemical shift , physics , molecule , biology , ecology , biochemistry , organic chemistry , snail , electrical engineering , engineering
The villin headpiece helical subdomain (HP36) is one of the best known model systems for computational studies of fast‐folding all‐α miniproteins. HP21 is a peptide fragment—derived from HP36—comprising only the first and second helices of the full domain. Experimental studies showed that although HP21 is mostly unfolded in solution, it does maintain some persistent native‐like structure as indicated by the analysis of NMR‐derived chemical shifts. Here we compare the experimental data for HP21 with the results obtained from a 15‐μs long folding molecular dynamics simulation performed in explicit water and with full electrostatics. We find that the simulation is in good agreement with the experiment and faithfully reproduces the major experimental findings, namely that (a) HP21 is disordered in solution with <10% of the trajectory corresponding to transiently stable structures, (b) the most highly populated conformer is a native‐like structure with an RMSD from the corresponding portion of the HP36 crystal structure of <1 Å, (c) the simulation‐derived chemical shifts—over the whole length of the trajectory—are in reasonable agreement with the experiment giving reduced χ 2 values of 1.6, 1.4, and 0.8 for the Δδ 13 C α , Δδ 13 CO, and Δδ 13 C β secondary shifts, respectively (becoming 0.8, 0.7, and 0.3 when only the major peptide conformer is considered), and finally, (d) the secondary structure propensity scores are in very good agreement with the experiment and clearly indicate the higher stability of the first helix. We conclude that folding molecular dynamics simulations can be a useful tool for the structural characterization of even marginally stable peptides.