Direct Probe of Iron Vibrations Elucidates NO Activation of Heme Proteins

摘要

Nuclear resonance vibrational spectroscopy(NRVS)is an emerging site-specific probe of active site vibrational dynamics in metalloproteins.1'2 NRVS is a synchrotron-based technique that uniquely targets the vibrations of a Mb'ssbauer nucleus,such as ~957)Fe,without interference from vibrations of other atoms,and reveals not only the frequency but also the(mean-squared)amplitude of all vibrations of the probe nucleus along the direction of the incident X-ray beam.Quantitative characterization of vibrational modes involving a reactive probe atom can illuminate mechanisms of complex biotnolecules.Reactions with hetne proteins mediate the physiological effects of nitric oxide(NO).The proposed trigger for activation of soluble guanylate cyclase(sGC)is rupture of the covalent Fe-His bond in the heme-containing domain upon NO binding to the Fe.