Abstract:
:We have measured, using infrared spectroscopy, the hydrogen/deuterium exchange rates of the amide protons in the photosynthetic antenna of Rhodospirillum rubrum. These measurements were made not only on the intact protein in detergent solution but also on two dissociated forms (B820 and B777). We have, on the basis of our knowledge of the structure of this protein, been able to assign the various groups of amide protons that exchange with different time constants to distinct regions of the protein. The most protected group of protons that we observe exchanging with time constants near 6000 min we assign to the transmembrane helices. The slow exchange rates measured for the amide protons of the transmembrane helices of this protein in detergent solution may indicate a destabilization of the helices in detergent solution compared with the membrane. This group of protons is progressively destabilized by stepwise dissociation of the antenna protein, and this destabilization is greater than we can account for by increases in solvent accessibility. We suggest that the observed loss of amide proton protection in the transmembrane helices as they are dissociated might be due to an increase in the helix flexibility and breathing motions as interactions between helices are reduced.
journal_name
Biophys Jjournal_title
Biophysical journalauthors
Sturgis J,Robert B,Goormaghtigh Edoi
10.1016/S0006-3495(98)74022-6subject
Has Abstractpub_date
1998-02-01 00:00:00pages
988-94issue
2 Pt 1eissn
0006-3495issn
1542-0086pii
S0006-3495(98)74022-6journal_volume
74pub_type
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