Modeling Sample Disorder in Site-Specific Dichroism Studies of Uniaxial Systems

Itamar Kass, Eyal Arbely, Isaiah T. Arkin*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


Site-specific infrared dichroism is an emerging method capable of proposing a model for the backbone structure of a transmembrane α-helix within a helical bundle. Dichroism measurements of single, isotopically enhanced vibrational modes (e.g., Amide I 13C=18O or Gly CD2 stretching modes) can yield precise orientational restraints for the monomer helix protomer that can be used as refinement constraints in model building of the entire helical bundle. Essential, however, for the interpretation of the dichroism measurements, is an accurate modeling of the sample disorder. In this study we derive an enhanced and more realistic modeling of the sample disorder based on a Gaussian distribution of the chromophore around a particular angle. The enhanced utility of the Gaussian model is exemplified by the comparative data analysis based on the aforementioned model to previously employed models.

Original languageAmerican English
Pages (from-to)2502-2507
Number of pages6
JournalBiophysical Journal
Issue number4
StatePublished - Apr 2004

Bibliographical note

Funding Information:
This research was supported in part by a grant from the Israel Science Foundation (784/01) to I.T.A.


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