@article{35512f3ffbce441faa15783676c97a42,
title = "Metalloprotein entatic control of ligand-metal bonds quantified by ultrafast x-ray spectroscopy",
abstract = "The multifunctional protein cytochrome c (cyt c) plays key roles in electron transport and apoptosis, switching function by modulating bonding between a heme iron and the sulfur in a methionine residue. This Fe-S(Met) bond is too weak to persist in the absence of protein constraints.We ruptured the bond in ferrous cyt c using an optical laser pulse and monitored the bond reformation within the protein active site using ultrafast x-ray pulses from an x-ray free-electron laser, determining that the Fe-S(Met) bond enthalpy is ∼4 kcal/mol stronger than in the absence of protein constraints.The 4 kcal/mol is comparable with calculations of stabilization effects in other systems, demonstrating how biological systems use an entatic state for modest yet accessible energetics to modulate chemical function.",
author = "Mara, {Michael William} and Hadt, {Ryan G.} and Reinhard, {Marco Eli} and Thomas Kroll and Hyeongtaek Lim and Hartsock, {Robert W.} and Roberto Alonso-Mori and Matthieu Chollet and Glownia, {James M.} and Silke Nelson and Dimosthenis Sokaras and Kristjan Kunnus and Hodgson, {Keith O.} and Britt Hedman and Uwe Bergmann and Gaffney, {Kelly J.} and Solomon, {Edward I.}",
note = "Funding Information: Use of the Linac Coherent Light Source (LCLS) and the Stanford Synchrotron Radiation Lightsource (SSRL) of the SLAC National Accelerator Laboratory is supported by the U.S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences under contract DE-AC02-76SF00515. The SSRL Structural Molecular Biology Program is supported by the DOE Office of Biological and Environmental Research and by the National Institutes of Health, National Institute of General Medical Sciences (P41GM103393). This research was supported by the National Institute of General Medical Sciences of the National Institutes of Health under award R01GM040392 (E.I.S.). R.W.H., K.K., and K.J.G. acknowledge support from the Atomic, Molecular, and Optical Sciences program within the Chemical Sciences, Geosciences, and Biosciences Division of the Office of Basic Energy Sciences, Office of Science, DOE. M.E.R. acknowledges the Swiss National Science Foundation, project 158890. H.L. acknowledges an Abbott Laboratories graduate fellowship. R.G.H. is currently an Enrico Fermi Fellow at Argonne National Laboratory. All data are reported in the main text, figures, and supplementary material Publisher Copyright: {\textcopyright} The Authors, some rights reserved.",
year = "2017",
month = jun,
day = "23",
doi = "10.1126/science.aam6203",
language = "English (US)",
volume = "356",
pages = "1276--1280",
journal = "Science",
issn = "0036-8075",
publisher = "American Association for the Advancement of Science",
number = "6344",
}