Do proteins at low temperature behave as glasses? A single-molecule study.
We have recorded long spectral diffusion trajectories from individual LH2 pigment-protein complexes from the purple bacterium Rhodobacter sphaeroides at 1.4 K. From these data, the spectral cumulants of the absorption lines of individual, protein-embedded BChl a pigments have been evaluated. It appears that the first and second cumulants cannot be described by the predictions of the well tested standard two-level system (TLS) model for spectral diffusion in glasses. The results of the present study clearly show that there is a fundamental difference between the relaxation behavior of our test protein and that of glasses.
Baier
Jürgen
J
Experimental Physics IV and BIMF, University of Bayreuth, 95440 Bayreuth, Germany.
Richter
Martin F
MF
Cogdell
Richard J
RJ
Oellerich
Silke
S
Köhler
Jürgen
J
D005898:Glass / Q000737:chemistry; D011506:Proteins / Q000737:chemistry*; D012242:Rhodobacter sphaeroides / Q000737:chemistry; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence / Q000379:methods; D013696:Temperature
D011506:Proteins