Dynamics of Proteins and Biomembranes

The fluorescence-photochrome technique was first applied to study the molecular dynamics of a stilbene fiuorescence-photochrome molecule, SITC, attached covalently to the terminal amino group of sperm whale myoglobin [18]. The same myoglobin residue was also labeled with a spin label, 4-iodoacetamide-TEMPO. The kinetics of the stilbene trans-cis photoisomerization (k pp) and the rotational diffusion frequency of nitroxide radicals (v ) was monitored by fiuorescence and E S R 

The FPM was applied to the study of E. coli membrane dynamics using 4-dimethylamino-4 -aminostilbene (DMAAS) [13]. Considering the dependence of the glycerol viscosity on temperature and then the effect of viscosity on the correlation time of rotation of a nitroxide radical (Xc), In kjso was plotted against Xc- In the low 

the fluorescence-photochrome method may, in certain conditions, gain advantage over conventional fluorescence, and spin labeling is simpler, more sensitive, and informative. 

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