Protein Fluorescence Lecture Notes

This set of flashcards covers the key vocabulary and concepts related to protein fluorescence as discussed in the lecture notes.

Stokes Shift

The difference between the wavelength of maximum absorbance and emission.

Fluorescence Lifetime

The average time a fluorophore remains in the excited state before emitting a photon, typically between 1-10 ns for proteins.

Fluorimeter

An instrument used to measure fluorescence, sensitive and often used at 90 degrees to the incident beam.

Intrinsic Fluorescence

Fluorescence that arises from chemical groups naturally found in proteins, such as Phenylalanine, Tyrosine, and Tryptophan.

Extrinsic Fluorescence

Fluorescence resulting from chemical groups added to a protein or through fusion with a naturally fluorescent protein like GFP.

Quantum Yield (Q)

The ratio of the number of molecules that fluoresce to the total number of excited molecules.

Energy Transfer

The process that occurs between two fluorophores when the emission spectrum of the donor overlaps with the absorbance spectrum of the acceptor.

Fluorescence Anisotropy

A measurement of the rotation of a fluorophore that can indicate dynamic properties within the sample.

Förster Distance (Ro)

The distance at which the efficiency of energy transfer between a donor and acceptor is 50%.

Fluorescent Probes

Dyes developed for biological applications, characterized by high absorbance, quantum yield, and photo-stability.

Hydrophobic Surfaces

Non-fluorescent surfaces in aqueous solution that become highly fluorescent when bound to specific dyes, indicating interaction.

Example of FRET

Energy transfer from Tryptophan (Tyr) to another fluorophore, dependent on the proximity and orientation of the molecules.

Emission Spectrum

The spectrum of light emitted from a fluorophore, typically studied to characterize the fluorescent properties of samples.

Absorbance

The measure of light absorbed by a sample, which varies with the angle between the transition dipole moment and the polarization of the incoming light.

Monochromators

Devices in fluorimetry that select specific wavelengths for excitation or emission measurements.

Fluorescent Intensity

The strength of the fluorescence signal which can be impacted by the microenvironment and quenching effects.