000181762 001__ 181762
000181762 005__ 20180913061555.0
000181762 0247_ $$2doi$$a10.1073/pnas.0808581106
000181762 022__ $$a1091-6490
000181762 037__ $$aARTICLE
000181762 245__ $$aLocal conformational dynamics in alpha-helices measured by fast triplet transfer
000181762 260__ $$c2009
000181762 269__ $$a2009
000181762 336__ $$aJournal Articles
000181762 520__ $$aCoupling fast triplet-triplet energy transfer (TTET) between xanthone and naphthylalanine to the helix-coil equilibrium in alanine-based peptides allowed the observation of local equilibrium fluctuations in alpha-helices on the nanoseconds to microseconds time scale. The experiments revealed faster helix unfolding in the terminal regions compared with the central parts of the helix with time constants varying from 250 ns to 1.4 micros at 5 degrees C. Local helix formation occurs with a time constant of approximately 400 ns, independent of the position in the helix. Comparing the experimental data with simulations using a kinetic Ising model showed that the experimentally observed dynamics can be explained by a 1-dimensional boundary diffusion with position-independent elementary time constants of approximately 50 ns for the addition and of approximately 65 ns for the removal of an alpha-helical segment. The elementary time constant for helix growth agrees well with previously measured time constants for formation of short loops in unfolded polypeptide chains, suggesting that helix elongation is mainly limited by a conformational search.
000181762 6531_ $$aEnergy Transfer
000181762 700__ $$0246394$$aFierz, Beat$$g224007
000181762 700__ $$aReiner, Andreas
000181762 700__ $$aKiefhaber, Thomas
000181762 773__ $$j106$$k4$$q1057-62$$tProceedings of the National Academy of Sciences of the United States of America
000181762 909C0 $$0252463$$pLCBM$$xU12613
000181762 909CO $$ooai:infoscience.tind.io:181762$$pSB$$particle
000181762 917Z8 $$x148230
000181762 937__ $$aEPFL-ARTICLE-181762
000181762 973__ $$aOTHER$$rREVIEWED$$sPUBLISHED
000181762 980__ $$aARTICLE