Protein dynamics: conformational disorder, vibrational coupling and anharmonicity in deoxy-hemoglobin and myoglobin

✍ Scribed by Antonio Cupane; Maurizio Leone; Eugenio Vitrano

• Publisher: Springer
• Year: 1993
• Tongue: English
• Weight: 784 KB
• Volume: 21
• Category: Article
• ISSN: 1432-1017
• DOI: 10.1007/bf00185865

✦ Synopsis

In this work we study the temperature dependence of the Soret band lineshape of deoxymyoglobin and deoxyhemoglobin, in the range 300 20 K. To fit the measured spectra we use an approach originally proposed by Champion and coworkers . The band profile is modelled as a Voigt function that accounts for the coupling with low frequency vibrational modes, whereas the coupling with high frequency modes is responsible for the vibronic structure of the spectra. Moreover, owing to the position of the iron atom out of the mean heine plane, inhomogeneous broadening brings about a non-Gaussian distribution of 0-0 electronic transition frequencies. The reported analysis enables us to isolate the various contributions to the overall bandwidth, and their temperature dependence points out the relevance of low frequency vibrations and of large scale anharmonic motions starting at temperatures higher than 170 K. Information on the mean ironheme plane distance and on its temperature dependence, as well as on the heine pocket conformational disorder, is also obtained.