Biochemistry - The Chemical Reactions of Living Cells, Volume 3 - D. Metzler 1980

Light in Biology
Fluorescence and Phosphorescence
Fluorescence Polarization

Light emitted by excited molecules immediately after absorption is always partially polarized, regardless of whether the exciting light was plane-polarized. Over time, as the molecules adopt a random orientation, the polarization of the luminescence emission disappears. By knowing the degree of fluorescence depolarization, valuable information can be obtained on the rotational speed of macromolecules bound to the fluorescent chromophore, as well as on the mobility of chromophore groups within the macromolecule, Cell membrane, etc. [52, 53, 55, 61]. The rotational speed derived from polarization degree measurements depends heavily on the viscosity of the medium [see equation (6-32)]. The Introduction of fluorescent "probes" (such as 1-anilinonaphthalene-8-sulfonate) into membranes, contractile fibers, etc., makes it possible to study changes in mobility that may accompany shifts in physiological conditions. In this way, potential molecular alterations in membranes during Nerve Impulse propagation and in Mitochondria during electron transport have been investigated [61, 62].

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Last update: 06/08/2026

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