Kindling red fluorescent protein KFP-Red

- Photoactivatable red fluorescent protein
- Kindled by green laser that does not damage cells and tissues
- Can be kindled reversibly or irreversibly
- Recommended for tracking cell and cellular organelle movement

Recommended filter sets and activating lasers

KFP-Red is non-fluorescent before light activation. Upon green-light irradiation, the protein kindles to its red fluorescent form. Green light of low intensity (e.g. 1% power scanning green laser, HeNe laser line 543 nm, 1 mW, scan per 10 seconds; the number of scans is not limited) does not cause kindling and may be used as excitation light for KFP-Red visualization.

Scanning with about 5-10% power laser results in reversible kindling of KFP-Red. More intensive-light irradiation is required for irreversible KFP-Red kindling (e.g. irradiation for 20 seconds in fast mode with a 30% power green laser light induces irreversible kindling of KFP-Red in mitochondria within the irradiated field). Irradiation with weak blue laser light causes instantaneous quenching of reversibly kindled KFP-Red, whereas for the irreversibly kindled KFP-Red, quenching is not so pronounced.

TRITC filter set or similar can be used for visualization of activated KFP-Red. Omega Optical filter sets QMAX-Red and XF174 are recommended.

Kindling effect depends on temperature. Light intensity required for kindling goes down when the temperature decreases and goes up when the temperature rises. This property can be used to achieve kindling at lower light intensities by sample cooling.